iOS
UIKit Dynamics

Wprowadzenie

Uwagi

label.frame = CGRect(x: 0.0, y: 0.0, width: label.intrinsicContentSize.width, height: label.intrinsicContentSize.height)
dynamicAnimator.updateItem(usingCurrentState: label)

self.label.frame = CGRectMake(0.0, 0.0, self.label.intrinsicContentSize.width, self.label.intrinsicContentSize.height);
[self.dynamicAnimator updateItemUsingCurrentState: self.label];

Falling Square

Narysujmy kwadrat w środku naszego widoku i spraw, aby spadł na dół i zatrzymał się na dolnej krawędzi kolizującej z dolną granicą ekranu.

@IBOutlet var animationView: UIView!
var squareView:UIView!
var collision: UICollisionBehavior!
var animator: UIDynamicAnimator!
var gravity: UIGravityBehavior!

override func viewDidLoad() {
    super.viewDidLoad()
    let squareSize = CGSize(width: 30.0, height: 30.0)
    let centerPoint = CGPoint(x: self.animationView.bounds.midX - (squareSize.width/2), y: self.animationView.bounds.midY - (squareSize.height/2))
    let frame = CGRect(origin: centerPoint, size: squareSize)
    squareView = UIView(frame: frame)
    squareView.backgroundColor = UIColor.orangeColor()
    animationView.addSubview(squareView)
    animator = UIDynamicAnimator(referenceView: view)
    gravity = UIGravityBehavior(items: [squareView])
    animator.addBehavior(gravity)
    collision = UICollisionBehavior(items: [square])
    collision.translatesReferenceBoundsIntoBoundary = true
    animator.addBehavior(collision)
}

Widok Flick na podstawie prędkości gestu

Ten przykład pokazuje, jak widok może śledzić gest panoramy i wychodzić w sposób oparty na fizyce.

Szybki

class ViewController: UIViewController
{
    // Adjust to change speed of view from flick
    let magnitudeMultiplier: CGFloat = 0.0008
    
    lazy var dynamicAnimator: UIDynamicAnimator =
    {
        let dynamicAnimator = UIDynamicAnimator(referenceView: self.view)
        return dynamicAnimator
    }()

    lazy var gravity: UIGravityBehavior =
    {
        let gravity = UIGravityBehavior(items: [self.orangeView])
        return gravity
    }()
    
    lazy var collision: UICollisionBehavior =
    {
        let collision = UICollisionBehavior(items: [self.orangeView])
        collision.translatesReferenceBoundsIntoBoundary = true
        return collision
    }()
    
    lazy var orangeView: UIView =
    {
        let widthHeight: CGFloat = 40.0
        let orangeView = UIView(frame: CGRect(x: 0.0, y: 0.0, width: widthHeight, height: widthHeight))
        orangeView.backgroundColor = UIColor.orange
        self.view.addSubview(orangeView)
        return orangeView
    }()
    
    lazy var panGesture: UIPanGestureRecognizer =
    {
        let panGesture = UIPanGestureRecognizer(target: self, action: #selector(self.handlePan(sender:)))
        return panGesture
    }()
    
    lazy var attachment: UIAttachmentBehavior =
    {
        let attachment = UIAttachmentBehavior(item: self.orangeView, attachedToAnchor: .zero)
        return attachment
    }()

    override func viewDidLoad()
    {
        super.viewDidLoad()
        dynamicAnimator.addBehavior(gravity)
        dynamicAnimator.addBehavior(collision)
        orangeView.addGestureRecognizer(panGesture)
    }
    
    override func viewDidLayoutSubviews()
    {
        super.viewDidLayoutSubviews()
        orangeView.center = view.center
        dynamicAnimator.updateItem(usingCurrentState: orangeView)
    }
    
    func handlePan(sender: UIPanGestureRecognizer)
    {
        let location = sender.location(in: view)
        let velocity = sender.velocity(in: view)
        let magnitude = sqrt((velocity.x * velocity.x) + (velocity.y * velocity.y))
        switch sender.state
        {
        case .began:
            attachment.anchorPoint = location
            dynamicAnimator.addBehavior(attachment)
        case .changed:
            attachment.anchorPoint = location
        case .cancelled, .ended, .failed, .possible:
            let push = UIPushBehavior(items: [self.orangeView], mode: .instantaneous)
            push.pushDirection = CGVector(dx: velocity.x, dy: velocity.y)
            push.magnitude = magnitude * magnitudeMultiplier
            dynamicAnimator.removeBehavior(attachment)
            dynamicAnimator.addBehavior(push)
        }
    }
}

Cel C

@interface ViewController ()

@property (nonatomic, assign) CGFloat magnitudeMultiplier;
@property (nonatomic, strong) UIDynamicAnimator *dynamicAnimator;
@property (nonatomic, strong) UIGravityBehavior *gravity;
@property (nonatomic, strong) UICollisionBehavior *collision;
@property (nonatomic, strong) UIView *orangeView;
@property (nonatomic, strong) UIPanGestureRecognizer *panGesture;
@property (nonatomic, strong) UIAttachmentBehavior *attachment;

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self.dynamicAnimator addBehavior:self.gravity];
    [self.dynamicAnimator addBehavior:self.collision];
    [self.orangeView addGestureRecognizer:self.panGesture];
    // Adjust to change speed of view from flick
    self.magnitudeMultiplier = 0.0008f;
}

- (void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];
    self.orangeView.center = self.view.center;
    [self.dynamicAnimator updateItemUsingCurrentState:self.orangeView];
}

- (void)handlePan:(UIPanGestureRecognizer *)sender
{
    CGPoint location = [sender locationInView:self.view];
    CGPoint velocity = [sender velocityInView:self.view];
    CGFloat magnitude = sqrt((velocity.x * velocity.x) + (velocity.y * velocity.y));
    if (sender.state == UIGestureRecognizerStateBegan)
    {
        self.attachment.anchorPoint = location;
        [self.dynamicAnimator addBehavior:self.attachment];
    }
    else if (sender.state == UIGestureRecognizerStateChanged)
    {
        self.attachment.anchorPoint = location;
    }
    else if (sender.state == UIGestureRecognizerStateCancelled ||
             sender.state == UIGestureRecognizerStateEnded ||
             sender.state == UIGestureRecognizerStateFailed ||
             sender.state == UIGestureRecognizerStatePossible)
    {
        UIPushBehavior *push = [[UIPushBehavior alloc] initWithItems:@[self.orangeView] mode:UIPushBehaviorModeInstantaneous];
        push.pushDirection = CGVectorMake(velocity.x, velocity.y);
        push.magnitude = magnitude * self.magnitudeMultiplier;
        [self.dynamicAnimator removeBehavior:self.attachment];
        [self.dynamicAnimator addBehavior:push];
    }
}

#pragma mark - Lazy Init
- (UIDynamicAnimator *)dynamicAnimator
{
    if (!_dynamicAnimator)
    {
        _dynamicAnimator = [[UIDynamicAnimator alloc]initWithReferenceView:self.view];
    }
    return _dynamicAnimator;
}

- (UIGravityBehavior *)gravity
{
    if (!_gravity)
    {
        _gravity = [[UIGravityBehavior alloc]initWithItems:@[self.orangeView]];
    }
    return _gravity;
}

- (UICollisionBehavior *)collision
{
    if (!_collision)
    {
        _collision = [[UICollisionBehavior alloc]initWithItems:@[self.orangeView]];
        _collision.translatesReferenceBoundsIntoBoundary = YES;
    }
    return _collision;
}

- (UIView *)orangeView
{
    if (!_orangeView)
    {
        CGFloat widthHeight = 40.0f;
        _orangeView = [[UIView alloc]initWithFrame:CGRectMake(0.0, 0.0, widthHeight, widthHeight)];
        _orangeView.backgroundColor = [UIColor orangeColor];
        [self.view addSubview:_orangeView];
    }
    return _orangeView;
}

- (UIPanGestureRecognizer *)panGesture
{
    if (!_panGesture)
    {
        _panGesture = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(handlePan:)];
    }
    return _panGesture;
}

- (UIAttachmentBehavior *)attachment
{
    if (!_attachment)
    {
        _attachment = [[UIAttachmentBehavior alloc]initWithItem:self.orangeView attachedToAnchor:CGPointZero];
    }
    return _attachment;
}

@end

Efekt „lepkich rogów” za pomocą UIFieldBehaviors

Ten przykład pokazuje, jak osiągnąć efekt podobny do FaceTime, gdy widok jest przyciągany do punktu po wejściu do określonego regionu, w tym przypadku dwóch regionów u góry i u dołu.

Szybki

class ViewController: UIViewController
{
    lazy var dynamicAnimator: UIDynamicAnimator =
    {
        let dynamicAnimator = UIDynamicAnimator(referenceView: self.view)
        return dynamicAnimator
    }()
    
    lazy var collision: UICollisionBehavior =
    {
        let collision = UICollisionBehavior(items: [self.orangeView])
        collision.translatesReferenceBoundsIntoBoundary = true
        return collision
    }()
    
    lazy var fieldBehaviors: [UIFieldBehavior] =
    {
        var fieldBehaviors = [UIFieldBehavior]()
        for _ in 0 ..< 2
        {
            let field = UIFieldBehavior.springField()
            field.addItem(self.orangeView)
            fieldBehaviors.append(field)
        }
        return fieldBehaviors
    }()
    
    lazy var itemBehavior: UIDynamicItemBehavior =
    {
        let itemBehavior = UIDynamicItemBehavior(items: [self.orangeView])
        // Adjust these values to change the "stickiness" of the view
        itemBehavior.density = 0.01
        itemBehavior.resistance = 10
        itemBehavior.friction = 0.0
        itemBehavior.allowsRotation = false
        return itemBehavior
    }()
    
    lazy var orangeView: UIView =
    {
        let widthHeight: CGFloat = 40.0
        let orangeView = UIView(frame: CGRect(x: 0.0, y: 0.0, width: widthHeight, height: widthHeight))
        orangeView.backgroundColor = UIColor.orange
        self.view.addSubview(orangeView)
        return orangeView
    }()
    
    lazy var panGesture: UIPanGestureRecognizer =
    {
        let panGesture = UIPanGestureRecognizer(target: self, action: #selector(self.handlePan(sender:)))
        return panGesture
    }()
    
    lazy var attachment: UIAttachmentBehavior =
    {
        let attachment = UIAttachmentBehavior(item: self.orangeView, attachedToAnchor: .zero)
        return attachment
    }()

    override func viewDidLoad()
    {
        super.viewDidLoad()
        dynamicAnimator.addBehavior(collision)
        dynamicAnimator.addBehavior(itemBehavior)
        for field in fieldBehaviors
        {
            dynamicAnimator.addBehavior(field)
        }
        
        orangeView.addGestureRecognizer(panGesture)
    }
    
    override func viewDidLayoutSubviews()
    {
        super.viewDidLayoutSubviews()
        
        orangeView.center = view.center
        dynamicAnimator.updateItem(usingCurrentState: orangeView)
        
        for (index, field) in fieldBehaviors.enumerated()
        {
            field.position = CGPoint(x: view.bounds
                .midX, y:  view.bounds.height * (0.25 + 0.5 * CGFloat(index)))
            field.region = UIRegion(size: CGSize(width: view.bounds.width, height: view.bounds.height * 0.5))
        }
    }
    
    func handlePan(sender: UIPanGestureRecognizer)
    {
        let location = sender.location(in: view)
        let velocity = sender.velocity(in: view)
        switch sender.state
        {
        case .began:
            attachment.anchorPoint = location
            dynamicAnimator.addBehavior(attachment)
        case .changed:
            attachment.anchorPoint = location
        case .cancelled, .ended, .failed, .possible:
            itemBehavior.addLinearVelocity(velocity, for: self.orangeView)
            dynamicAnimator.removeBehavior(attachment)
        }
    }
}

Cel C

@interface ViewController ()

@property (nonatomic, strong) UIDynamicAnimator *dynamicAnimator;
@property (nonatomic, strong) UICollisionBehavior *collision;
@property (nonatomic, strong) UIAttachmentBehavior *attachment;
@property (nonatomic, strong) UIDynamicItemBehavior *itemBehavior;
@property (nonatomic, strong) NSArray <UIFieldBehavior *> *fieldBehaviors;
@property (nonatomic, strong) UIView *orangeView;
@property (nonatomic, strong) UIPanGestureRecognizer *panGesture;

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self.dynamicAnimator addBehavior:self.collision];
    [self.dynamicAnimator addBehavior:self.itemBehavior];
    for (UIFieldBehavior *field in self.fieldBehaviors)
    {
        [self.dynamicAnimator addBehavior:field];
    }
    
    [self.orangeView addGestureRecognizer:self.panGesture];
}

- (void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];
    self.orangeView.center = self.view.center;
    [self.dynamicAnimator updateItemUsingCurrentState:self.orangeView];
    
    for (NSInteger i = 0; i < self.fieldBehaviors.count; i++)
    {
        UIFieldBehavior *field = self.fieldBehaviors[i];
        field.position = CGPointMake(CGRectGetMidX(self.view.bounds), CGRectGetHeight(self.view.bounds) * (0.25f + 0.5f * i));
        field.region = [[UIRegion alloc]initWithSize:CGSizeMake(CGRectGetWidth(self.view.bounds), CGRectGetHeight(self.view.bounds) * 0.5)];
    }
}

- (void)handlePan:(UIPanGestureRecognizer *)sender
{
    CGPoint location = [sender locationInView:self.view];
    CGPoint velocity = [sender velocityInView:self.view];
    if (sender.state == UIGestureRecognizerStateBegan)
    {
        self.attachment.anchorPoint = location;
        [self.dynamicAnimator addBehavior:self.attachment];
    }
    else if (sender.state == UIGestureRecognizerStateChanged)
    {
        self.attachment.anchorPoint = location;
    }
    else if (sender.state == UIGestureRecognizerStateCancelled ||
             sender.state == UIGestureRecognizerStateEnded ||
             sender.state == UIGestureRecognizerStateFailed ||
             sender.state == UIGestureRecognizerStatePossible)
    {
        [self.itemBehavior addLinearVelocity:velocity forItem:self.orangeView];
        [self.dynamicAnimator removeBehavior:self.attachment];
    }
}

#pragma mark - Lazy Init
- (UIDynamicAnimator *)dynamicAnimator
{
    if (!_dynamicAnimator)
    {
        _dynamicAnimator = [[UIDynamicAnimator alloc]initWithReferenceView:self.view];
    }
    return _dynamicAnimator;
}

- (UICollisionBehavior *)collision
{
    if (!_collision)
    {
        _collision = [[UICollisionBehavior alloc]initWithItems:@[self.orangeView]];
        _collision.translatesReferenceBoundsIntoBoundary = YES;
    }
    return _collision;
}

- (NSArray <UIFieldBehavior *> *)fieldBehaviors
{
    if (!_fieldBehaviors)
    {
        NSMutableArray *fields = [[NSMutableArray alloc]init];
        for (NSInteger i =  0; i < 2; i++)
        {
            UIFieldBehavior *field = [UIFieldBehavior springField];
            [field addItem:self.orangeView];
            [fields addObject:field];
        }
        _fieldBehaviors = fields;
    }
    return _fieldBehaviors;
}

- (UIDynamicItemBehavior *)itemBehavior
{
    if (!_itemBehavior)
    {
        _itemBehavior = [[UIDynamicItemBehavior alloc]initWithItems:@[self.orangeView]];
        // Adjust these values to change the "stickiness" of the view
        _itemBehavior.density = 0.01;
        _itemBehavior.resistance = 10;
        _itemBehavior.friction = 0.0;
        _itemBehavior.allowsRotation = NO;
    }
    return _itemBehavior;
}

- (UIView *)orangeView
{
    if (!_orangeView)
    {
        CGFloat widthHeight = 40.0f;
        _orangeView = [[UIView alloc]initWithFrame:CGRectMake(0.0, 0.0, widthHeight, widthHeight)];
        _orangeView.backgroundColor = [UIColor orangeColor];
        [self.view addSubview:_orangeView];
    }
    return _orangeView;
}

- (UIPanGestureRecognizer *)panGesture
{
    if (!_panGesture)
    {
        _panGesture = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(handlePan:)];
    }
    return _panGesture;
}

- (UIAttachmentBehavior *)attachment
{
    if (!_attachment)
    {
        _attachment = [[UIAttachmentBehavior alloc]initWithItem:self.orangeView attachedToAnchor:CGPointZero];
    }
    return _attachment;
}

@end

Więcej informacji na temat UIFieldBehaviors można znaleźć w sesji WWDC 2015 „Co nowego w UIKit Dynamics and Visual Effects” i dołączonym przykładowym kodzie .

UIDynamicBehavior Driven Custom Transition

Ten przykład pokazuje, jak utworzyć niestandardowe przejście prezentacji sterowane przez złożony UIDynamicBehavior . Możemy zacząć od stworzenia prezentującego kontrolera widoku, który zaprezentuje modal.

Szybki

class PresentingViewController: UIViewController
{
    lazy var button: UIButton =
    {
        let button = UIButton()
        button.translatesAutoresizingMaskIntoConstraints = false
        self.view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive
            = true
        button.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
        button.setTitle("Present", for: .normal)
        button.setTextColor(UIColor.blue, for: .normal)
        
        return button
    }()
    
    override func viewDidLoad()
    {
        super.viewDidLoad()
        button.addTarget(self, action: #selector(self.didPressPresent), for: .touchUpInside)
    }
    
    func didPressPresent()
    {
        let modal = ModalViewController()
        modal.view.frame = CGRect(x: 0.0, y: 0.0, width: 200.0, height: 200.0)
        modal.modalPresentationStyle = .custom
        modal.transitioningDelegate = modal
        self.present(modal, animated: true)
    }
}

Cel C

@interface PresentingViewController ()
@property (nonatomic, strong) UIButton *button;
@end

@implementation PresentingViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self.button addTarget:self action:@selector(didPressPresent) forControlEvents:UIControlEventTouchUpInside];
}

- (void)didPressPresent
{
    ModalViewController *modal = [[ModalViewController alloc] init];
    modal.view.frame = CGRectMake(0.0, 0.0, 200.0, 200.0);
    modal.modalPresentationStyle = UIModalPresentationCustom;
    modal.transitioningDelegate = modal;
    [self presentViewController:modal animated:YES completion:nil];
}

- (UIButton *)button
{
    if (!_button)
    {
        _button = [[UIButton alloc] init];
        _button.translatesAutoresizingMaskIntoConstraints = NO;
        [self.view addSubview:_button];
        [_button.centerXAnchor constraintEqualToAnchor:self.view.centerXAnchor].active = YES;
        [_button.centerYAnchor constraintEqualToAnchor:self.view.centerYAnchor].active = YES;
        [_button setTitle:@"Present" forState:UIControlStateNormal];
        [_button setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    }
    return _button;
}

@end

Po naciśnięciu obecnego przycisku tworzymy ModalViewController i ustawiamy styl prezentacji na .custom i ustawiamy transitionDelegate dla siebie. Pozwoli nam to sprzedać animatora, który będzie sterował jego modalnym przejściem. Ustawiliśmy również ramkę widoku modal , aby była mniejsza niż pełny ekran.

Spójrzmy teraz na ModalViewController :

Szybki

class ModalViewController: UIViewController
{
    lazy var button: UIButton =
    {
        let button = UIButton()
        button.translatesAutoresizingMaskIntoConstraints = false
        self.view.addSubview(button)
        button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive
         = true
        button.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
        button.setTitle("Dismiss", for: .normal)
        button.setTitleColor(.white, for: .normal)
        
        return button
    }()
    
    override func viewDidLoad()
    {
        super.viewDidLoad()
        button.addTarget(self, action: #selector(self.didPressDismiss), for: .touchUpInside)
        view.backgroundColor = .red
        view.layer.cornerRadius = 15.0
    }
    
    func didPressDismiss()
    {
        dismiss(animated: true)
    }
}

extension ModalViewController: UIViewControllerTransitioningDelegate
{
    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning?
    {
        return DropOutAnimator(duration: 1.5, isAppearing: true)
    }
    
    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning?
    {
        return DropOutAnimator(duration: 4.0, isAppearing: false)
    }
}

Cel C

@interface ModalViewController () <UIViewControllerTransitioningDelegate>
@property (nonatomic, strong) UIButton *button;
@end

@implementation ModalViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self.button addTarget:self action:@selector(didPressPresent) forControlEvents:UIControlEventTouchUpInside];
    self.view.backgroundColor = [UIColor redColor];
    self.view.layer.cornerRadius = 15.0f;
}

- (void)didPressPresent
{
    [self dismissViewControllerAnimated:YES completion:nil];
}

- (UIButton *)button
{
    if (!_button)
    {
        _button = [[UIButton alloc] init];
        _button.translatesAutoresizingMaskIntoConstraints = NO;
        [self.view addSubview:_button];
        [_button.centerXAnchor constraintEqualToAnchor:self.view.centerXAnchor].active = YES;
        [_button.centerYAnchor constraintEqualToAnchor:self.view.centerYAnchor].active = YES;
        [_button setTitle:@"Dismiss" forState:UIControlStateNormal];
        [_button setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    }
    return _button;
}

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
{
    return [[DropOutAnimator alloc]initWithDuration: 1.5 appearing:YES];
}

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
{
    return [[DropOutAnimator alloc] initWithDuration:4.0 appearing:NO];
}

@end

Tutaj tworzymy kontroler widoku, który jest prezentowany. Również dlatego, że ModalViewController jest swoim własnym transitioningDelegate . ModalViewController jest również odpowiedzialny za vending obiektu, który będzie zarządzał jego animacją przejścia. Dla nas oznacza to przekazanie instancji naszej złożonej podklasy UIDynamicBehavior .

Nasz animator będzie miał dwa różne przejścia: jedno do prezentacji, a drugie do zwolnienia. Do prezentacji widok kontrolera widoku prezentującego pojawi się z góry. A jeśli chodzi o oddalenie, widok wydaje się kołysać z liny, a następnie wypada. Ponieważ DropOutAnimator jest zgodny z UIViewControllerAnimatedTransitioning większość tej pracy zostanie wykonana przy implementacji func animateTransition(using transitionContext: UIViewControllerContextTransitioning) .

Szybki

class DropOutAnimator: UIDynamicBehavior
{
    let duration: TimeInterval
    let isAppearing: Bool

    var transitionContext: UIViewControllerContextTransitioning?
    var hasElapsedTimeExceededDuration = false
    var finishTime: TimeInterval = 0.0
    var collisionBehavior: UICollisionBehavior?
    var attachmentBehavior: UIAttachmentBehavior?
    var animator: UIDynamicAnimator?

    init(duration: TimeInterval = 1.0,  isAppearing: Bool)
    {
        self.duration = duration
        self.isAppearing = isAppearing
        super.init()
    }
}

extension DropOutAnimator: UIViewControllerAnimatedTransitioning
{
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning)
    {
        // Get relevant views and view controllers from transitionContext
        guard let fromVC = transitionContext.viewController(forKey: .from),
              let toVC = transitionContext.viewController(forKey: .to),
              let fromView = fromVC.view,
              let toView = toVC.view else { return }
    
        let containerView = transitionContext.containerView
        let duration = self.transitionDuration(using: transitionContext)
    
        // Hold refrence to transitionContext to notify it of completion
        self.transitionContext = transitionContext
    
        // Create dynamic animator
        let animator = UIDynamicAnimator(referenceView: containerView)
        animator.delegate = self
        self.animator = animator
    
        // Presenting Animation
        if self.isAppearing
        {
            fromView.isUserInteractionEnabled = false
        
            // Position toView  just off-screen
            let fromViewInitialFrame = transitionContext.initialFrame(for: fromVC)
            var toViewInitialFrame = toView.frame
            toViewInitialFrame.origin.y -= toViewInitialFrame.height
            toViewInitialFrame.origin.x = fromViewInitialFrame.width * 0.5 - toViewInitialFrame.width * 0.5
            toView.frame = toViewInitialFrame
        
            containerView.addSubview(toView)
        
            // Prevent rotation and adjust bounce
            let bodyBehavior = UIDynamicItemBehavior(items: [toView])
            bodyBehavior.elasticity = 0.7
            bodyBehavior.allowsRotation = false
        
            // Add gravity at exaggerated magnitude so animation doesn't seem slow
            let gravityBehavior = UIGravityBehavior(items: [toView])
            gravityBehavior.magnitude = 10.0
        
            // Set collision bounds to include off-screen view and have collision in center 
            // where our final view should come to rest
            let collisionBehavior = UICollisionBehavior(items: [toView])
            let insets = UIEdgeInsets(top: toViewInitialFrame.minY, left: 0.0, bottom: fromViewInitialFrame.height * 0.5 - toViewInitialFrame.height * 0.5, right: 0.0)
            collisionBehavior.setTranslatesReferenceBoundsIntoBoundary(with: insets)
            self.collisionBehavior = collisionBehavior
        
            // Keep track of finish time in case we need to end the animator befor the animator pauses
            self.finishTime = duration + (self.animator?.elapsedTime ?? 0.0)
        
            // Closure that is called after every "tick" of the animator
            // Check if we exceed duration
            self.action =
            { [weak self] in
                guard let strongSelf = self,
                  (strongSelf.animator?.elapsedTime ?? 0.0) >= strongSelf.finishTime else { return }
                strongSelf.hasElapsedTimeExceededDuration = true
                strongSelf.animator?.removeBehavior(strongSelf)
            }
        
            // `DropOutAnimator` is a composit behavior, so add child behaviors to self
            self.addChildBehavior(collisionBehavior)
            self.addChildBehavior(bodyBehavior)
            self.addChildBehavior(gravityBehavior)
        
            // Add self to dynamic animator
            self.animator?.addBehavior(self)
        }
        // Dismissing Animation
        else
        {
            // Create allow rotation and have a elastic item
            let bodyBehavior = UIDynamicItemBehavior(items: [fromView])
            bodyBehavior.elasticity = 0.8
            bodyBehavior.angularResistance = 5.0
            bodyBehavior.allowsRotation = true
        
            // Create gravity with exaggerated magnitude
            let gravityBehavior = UIGravityBehavior(items: [fromView])
            gravityBehavior.magnitude = 10.0
        
            // Collision boundary is set to have a floor just below the bottom of the screen
            let collisionBehavior = UICollisionBehavior(items: [fromView])
            let insets = UIEdgeInsets(top: 0.0, left: -1000, bottom: -225, right: -1000)
            collisionBehavior.setTranslatesReferenceBoundsIntoBoundary(with: insets)
            self.collisionBehavior = collisionBehavior
        
            // Attachment behavior so view will have effect of hanging from a rope
            let offset = UIOffset(horizontal: 70.0, vertical: fromView.bounds.height * 0.5)
            var anchorPoint = CGPoint(x: fromView.bounds.maxX - 40.0, y: fromView.bounds.minY)
            anchorPoint = containerView.convert(anchorPoint, from: fromView)
            let attachmentBehavior = UIAttachmentBehavior(item: fromView, offsetFromCenter: offset, attachedToAnchor: anchorPoint)
            attachmentBehavior.frequency = 3.0
            attachmentBehavior.damping = 3.0
            self.attachmentBehavior = attachmentBehavior
        
            // `DropOutAnimator` is a composit behavior, so add child behaviors to self
            self.addChildBehavior(collisionBehavior)
            self.addChildBehavior(bodyBehavior)
            self.addChildBehavior(gravityBehavior)
            self.addChildBehavior(attachmentBehavior)
        
            // Add self to dynamic animator
            self.animator?.addBehavior(self)
        
            // Animation has two parts part one is hanging from rope. 
            // Part two is bouncying off-screen
            // Divide duration in two
            self.finishTime = (2.0 / 3.0) * duration + (self.animator?.elapsedTime ?? 0.0)
        
             // After every "tick" of animator check if past time limit
            self.action =
            { [weak self] in
                guard let strongSelf = self,
                  (strongSelf.animator?.elapsedTime ?? 0.0) >= strongSelf.finishTime else { return }
                strongSelf.hasElapsedTimeExceededDuration = true
                strongSelf.animator?.removeBehavior(strongSelf)
            }
        }
    
    }

    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval
    {
        // Return the duration of the animation
        return self.duration
    }
}

extension DropOutAnimator: UIDynamicAnimatorDelegate
{
    func dynamicAnimatorDidPause(_ animator: UIDynamicAnimator)
    {
      // Animator has reached stasis
      if self.isAppearing
      {
            // Check if we are out of time
            if self.hasElapsedTimeExceededDuration
            {
                // Move to final positions
                let toView = self.transitionContext?.viewController(forKey: .to)?.view
                let containerView = self.transitionContext?.containerView
                toView?.center = containerView?.center ?? .zero
                self.hasElapsedTimeExceededDuration = false
            }
            
            // Clean up and call completion
            self.transitionContext?.completeTransition(!(self.transitionContext?.transitionWasCancelled ?? false))
            self.childBehaviors.forEach { self.removeChildBehavior($0) }
            animator.removeAllBehaviors()
            self.transitionContext = nil
    }
    else
    {
        if let attachmentBehavior = self.attachmentBehavior
        {
            // If we have an attachment, we are at the end of part one and start part two.
            self.removeChildBehavior(attachmentBehavior)
            self.attachmentBehavior = nil
            animator.addBehavior(self)
            let duration = self.transitionDuration(using: self.transitionContext)
            self.finishTime = 1.0 / 3.0 * duration + animator.elapsedTime
        }
        else
        {
            // Clean up and call completion
            let fromView = self.transitionContext?.viewController(forKey: .from)?.view
            let toView = self.transitionContext?.viewController(forKey: .to)?.view
            fromView?.removeFromSuperview()
            toView?.isUserInteractionEnabled = true
            self.transitionContext?.completeTransition(!(self.transitionContext?.transitionWasCancelled ?? false))
            self.childBehaviors.forEach { self.removeChildBehavior($0) }
            animator.removeAllBehaviors()
            self.transitionContext = nil
        }
    }
}
}

Cel C

@interface ObjcDropOutAnimator() <UIDynamicAnimatorDelegate, UIViewControllerAnimatedTransitioning>
@property (nonatomic, strong) id<UIViewControllerContextTransitioning> transitionContext;
@property (nonatomic, strong) UIDynamicAnimator *animator;
@property (nonatomic, assign) NSTimeInterval finishTime;
@property (nonatomic, assign) BOOL elapsedTimeExceededDuration;
@property (nonatomic, assign, getter=isAppearing) BOOL appearing;
@property (nonatomic, assign) NSTimeInterval duration;
@property (nonatomic, strong) UIAttachmentBehavior *attachBehavior;
@property (nonatomic, strong) UICollisionBehavior * collisionBehavior;

@end

@implementation ObjcDropOutAnimator

- (instancetype)initWithDuration:(NSTimeInterval)duration appearing:(BOOL)appearing
{
    self = [super init];
    if (self)
    {
        _duration = duration;
        _appearing = appearing;
    }
    return self;
}

- (void) animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    // Get relevant views and view controllers from transitionContext
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIView *fromView = fromVC.view;
    UIView *toView = toVC.view;
    
    UIView *containerView = transitionContext.containerView;
    NSTimeInterval duration = [self transitionDuration:transitionContext];
    
    // Hold refrence to transitionContext to notify it of completion
    self.transitionContext = transitionContext;
    
    // Create dynamic animator
    UIDynamicAnimator *animator = [[UIDynamicAnimator alloc]initWithReferenceView:containerView];
    animator.delegate = self;
    self.animator = animator;
    
    // Presenting Animation
    if (self.isAppearing)
    {
        fromView.userInteractionEnabled = NO;
        
        // Position toView  just above screen
        CGRect fromViewInitialFrame = [transitionContext initialFrameForViewController:fromVC];
        CGRect toViewInitialFrame = toView.frame;
        toViewInitialFrame.origin.y -= CGRectGetHeight(toViewInitialFrame);
        toViewInitialFrame.origin.x = CGRectGetWidth(fromViewInitialFrame) * 0.5 - CGRectGetWidth(toViewInitialFrame) * 0.5;
        toView.frame = toViewInitialFrame;
        
        [containerView addSubview:toView];
        
        // Prevent rotation and adjust bounce
        UIDynamicItemBehavior *bodyBehavior = [[UIDynamicItemBehavior alloc]initWithItems:@[toView]];
        bodyBehavior.elasticity = 0.7;
        bodyBehavior.allowsRotation = NO;
        
        // Add gravity at exaggerated magnitude so animation doesn't seem slow
        UIGravityBehavior *gravityBehavior = [[UIGravityBehavior alloc]initWithItems:@[toView]];
        gravityBehavior.magnitude = 10.0f;
        
        // Set collision bounds to include off-screen view and have collision floor in center
        // where our final view should come to rest
        UICollisionBehavior *collisionBehavior = [[UICollisionBehavior alloc]initWithItems:@[toView]];
        UIEdgeInsets insets = UIEdgeInsetsMake(CGRectGetMinY(toViewInitialFrame), 0.0, CGRectGetHeight(fromViewInitialFrame) * 0.5 - CGRectGetHeight(toViewInitialFrame) * 0.5, 0.0);
        [collisionBehavior setTranslatesReferenceBoundsIntoBoundaryWithInsets:insets];
        self.collisionBehavior = collisionBehavior;
        
        // Keep track of finish time in case we need to end the animator befor the animator pauses
        self.finishTime = duration + self.animator.elapsedTime;
        
        // Closure that is called after every "tick" of the animator
        // Check if we exceed duration
        __weak ObjcDropOutAnimator *weakSelf = self;
        self.action = ^{
            __strong ObjcDropOutAnimator *strongSelf = weakSelf;
            if (strongSelf)
            {
                if (strongSelf.animator.elapsedTime >= strongSelf.finishTime)
                {
                    strongSelf.elapsedTimeExceededDuration = YES;
                    [strongSelf.animator removeBehavior:strongSelf];
                }
            }
        };
        
        // `DropOutAnimator` is a composit behavior, so add child behaviors to self
        [self addChildBehavior:collisionBehavior];
        [self addChildBehavior:bodyBehavior];
        [self addChildBehavior:gravityBehavior];
        
        // Add self to dynamic animator
        [self.animator addBehavior:self];
    }
    // Dismissing Animation
    else
    {
        // Allow rotation and have a elastic item
        UIDynamicItemBehavior *bodyBehavior = [[UIDynamicItemBehavior alloc] initWithItems:@[fromView]];
        bodyBehavior.elasticity = 0.8;
        bodyBehavior.angularResistance = 5.0;
        bodyBehavior.allowsRotation = YES;
        
        // Create gravity with exaggerated magnitude
        UIGravityBehavior *gravityBehavior = [[UIGravityBehavior alloc] initWithItems:@[fromView]];
        gravityBehavior.magnitude = 10.0f;
        
        // Collision boundary is set to have a floor just below the bottom of the screen
        UICollisionBehavior *collisionBehavior = [[UICollisionBehavior alloc] initWithItems:@[fromView]];
        UIEdgeInsets insets = UIEdgeInsetsMake(0, -1000, -225, -1000);
        [collisionBehavior setTranslatesReferenceBoundsIntoBoundaryWithInsets:insets];
        self.collisionBehavior = collisionBehavior;
        
        // Attachment behavior so view will have effect of hanging from a rope
        UIOffset offset = UIOffsetMake(70, -(CGRectGetHeight(fromView.bounds) / 2.0));
        
        CGPoint anchorPoint = CGPointMake(CGRectGetMaxX(fromView.bounds) - 40,
                                          CGRectGetMinY(fromView.bounds));
        anchorPoint = [containerView convertPoint:anchorPoint fromView:fromView];
        UIAttachmentBehavior *attachBehavior = [[UIAttachmentBehavior alloc] initWithItem:fromView offsetFromCenter:offset attachedToAnchor:anchorPoint];
        attachBehavior.frequency = 3.0;
        attachBehavior.damping = 0.3;
        attachBehavior.length = 40;
        self.attachBehavior = attachBehavior;
        
        // `DropOutAnimator` is a composit behavior, so add child behaviors to self
        [self addChildBehavior:collisionBehavior];
        [self addChildBehavior:bodyBehavior];
        [self addChildBehavior:gravityBehavior];
        [self addChildBehavior:attachBehavior];
        
        // Add self to dynamic animator
        [self.animator addBehavior:self];
        
        // Animation has two parts part one is hanging from rope.
        // Part two is bouncying off-screen
        // Divide duration in two
        self.finishTime = (2./3.) * duration + [self.animator elapsedTime];
        
        // After every "tick" of animator check if past time limit
        __weak ObjcDropOutAnimator *weakSelf = self;
        self.action = ^{
            __strong ObjcDropOutAnimator *strongSelf = weakSelf;
            if (strongSelf)
            {
                if ([strongSelf.animator elapsedTime] >= strongSelf.finishTime)
                {
                    strongSelf.elapsedTimeExceededDuration = YES;
                    [strongSelf.animator removeBehavior:strongSelf];
                }
            }
        };
    }
}

- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
    return self.duration;
}

- (void)dynamicAnimatorDidPause:(UIDynamicAnimator *)animator
{
    // Animator has reached stasis
    if (self.isAppearing)
    {
        // Check if we are out of time
        if (self.elapsedTimeExceededDuration)
        {
            // Move to final positions
            UIView *toView = [self.transitionContext viewControllerForKey:UITransitionContextToViewControllerKey].view;
            UIView *containerView = [self.transitionContext containerView];
            toView.center = containerView.center;
            self.elapsedTimeExceededDuration = NO;
        }
        
        // Clean up and call completion
        [self.transitionContext completeTransition:![self.transitionContext transitionWasCancelled]];
        for (UIDynamicBehavior *behavior in self.childBehaviors)
        {
            [self removeChildBehavior:behavior];
        }
        [animator removeAllBehaviors];
        self.transitionContext = nil;
    }
    // Dismissing
    else
    {
        if (self.attachBehavior)
        {
            // If we have an attachment, we are at the end of part one and start part two.
            [self removeChildBehavior:self.attachBehavior];
            self.attachBehavior = nil;
            [animator addBehavior:self];
            NSTimeInterval duration = [self transitionDuration:self.transitionContext];
            self.finishTime = 1./3. * duration + [animator elapsedTime];
        }
        else
        {
            // Clean up and call completion
            UIView *fromView = [self.transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey].view;
            UIView *toView = [self.transitionContext viewControllerForKey:UITransitionContextToViewControllerKey].view;
            [fromView removeFromSuperview];
            toView.userInteractionEnabled = YES;
            
            [self.transitionContext completeTransition:![self.transitionContext transitionWasCancelled]];
            for (UIDynamicBehavior *behavior in self.childBehaviors)
            {
                [self removeChildBehavior:behavior];
            }
            [animator removeAllBehaviors];
            self.transitionContext = nil;
        }
    }
}

Jako zachowanie złożone DropOutAnimator może łączyć wiele różnych zachowań, aby wykonywać swoje prezentacje i odrzucać animacje. DropOutAnimator pokazuje również, jak korzystać z bloku action zachowania, aby sprawdzać lokalizacje jego elementów, a także upływ czasu, którego można użyć do usunięcia widoków, które przesuwają się poza ekran lub przycinają animacje, które jeszcze nie osiągnęły zastoju.

Aby uzyskać więcej informacji, sesja WWDC 2013 „Zaawansowane techniki z UIKit Dynamics” oraz SOLPresentingFun

Przejście cieni z fizyką świata rzeczywistego za pomocą UIDynamicBehaviors

Ten przykład pokazuje, jak przeprowadzić interaktywną prezentację z fizyką „w świecie rzeczywistym” podobną do ekranu powiadomień iOS.

Na początek potrzebujemy prezentującego kontrolera widoku, od którego pojawi się cień. Ten kontroler widoku będzie również działał jako nasz UIViewControllerTransitioningDelegate dla naszego prezentowanego kontrolera widoku i będzie sprzedawał animatory dla naszego przejścia. Dlatego stworzymy instancje naszych interaktywnych animatorów (jeden do prezentacji, jeden do zwolnienia). Stworzymy również instancję kontrolera widoku cienia, który w tym przykładzie jest tylko kontrolerem widoku z etykietą. Ponieważ chcemy, aby ten sam gest panoramy sterował całą interakcją, przekazujemy odniesienia do kontrolera widoku i cienia do naszych interaktywnych animatorów.

Szybki

class ViewController: UIViewController
{
    var presentingAnimator: ShadeAnimator!
    var dismissingAnimator: ShadeAnimator!
    let shadeVC = ShadeViewController()
    
    lazy var label: UILabel =
    {
        let label = UILabel()
        label.textColor = .blue
        label.translatesAutoresizingMaskIntoConstraints = false
        self.view.addSubview(label)
        label.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true
        label.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
        return label
    }()
    
    override func viewDidLoad()
    {
        super.viewDidLoad()
        label.text = "Swipe Down From Top"
        presentingAnimator = ShadeAnimator(isAppearing: true, presentingVC: self, presentedVC: shadeVC, transitionDelegate: self)
        dismissingAnimator = ShadeAnimator(isAppearing: false, presentingVC: self, presentedVC: shadeVC, transitionDelegate: self)
    }
}
extension ViewController: UIViewControllerTransitioningDelegate
{
    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning?
    {
        return EmptyAnimator()
    }
    
    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning?
    {
        return EmptyAnimator()
    }
    
    func interactionControllerForPresentation(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?
    {
        return presentingAnimator
    }
    
    func interactionControllerForDismissal(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?
    {
        return dismissingAnimator
    }
}

Cel C

@interface ObjCViewController () <UIViewControllerTransitioningDelegate>
@property (nonatomic, strong) ShadeAnimator *presentingAnimator;
@property (nonatomic, strong) ShadeAnimator *dismissingAnimator;
@property (nonatomic, strong) UILabel *label;
@property (nonatomic, strong) ShadeViewController *shadeVC;
@end

@implementation ObjCViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.label.text = @"Swipe Down From Top";
    self.shadeVC = [[ShadeViewController alloc] init];
    self.presentingAnimator = [[ShadeAnimator alloc] initWithIsAppearing:YES presentingVC:self presentedVC:self.shadeVC transitionDelegate:self];
    self.dismissingAnimator = [[ShadeAnimator alloc] initWithIsAppearing:NO presentingVC:self presentedVC:self.shadeVC transitionDelegate:self];
}

- (UILabel *)label
{
    if (!_label)
    {
        _label = [[UILabel alloc] init];
        _label.textColor = [UIColor blueColor];
        _label.translatesAutoresizingMaskIntoConstraints = NO;
        [self.view addSubview:_label];
        [_label.centerXAnchor constraintEqualToAnchor:self.view.centerXAnchor].active = YES;
        [_label.centerYAnchor constraintEqualToAnchor:self.view.centerYAnchor].active = YES;
    }
    return _label;
}

#pragma mark - UIViewControllerTransitioningDelegate

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
{
    return [[EmptyAnimator alloc] init];
}

- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
{
    return [[EmptyAnimator alloc] init];
}

- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForPresentation:(id<UIViewControllerAnimatedTransitioning>)animator
{
    return self.presentingAnimator;
}

- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForDismissal:(id<UIViewControllerAnimatedTransitioning>)animator
{
    return self.dismissingAnimator;
}

@end

Chcemy, aby naprawdę zawsze prezentować nasz cień poprzez interaktywne przejście, ale ze względu na to, jak działa UIViewControllerTransitioningDelegate jeśli nie zwrócimy zwykłego kontrolera animacji, nasz kontroler interaktywny nigdy nie zostanie użyty. Z tego powodu EmptyAnimator klasę EmptyAnimator która jest zgodna z UIViewControllerAnimatedTransitioning .

Szybki

class EmptyAnimator: NSObject
{

}

extension EmptyAnimator: UIViewControllerAnimatedTransitioning
{
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning)
    {
        
    }
    
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval
    {
        return 0.0
    }
}

Cel C

@implementation EmptyAnimator

- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    
}

- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
    return 0.0;
}

@end

Wreszcie musimy faktycznie utworzyć ShadeAnimator który jest podklasą UIDynamicBehavior która jest zgodna z UIViewControllerInteractiveTransitioning .

Szybki

class ShadeAnimator: UIDynamicBehavior
{
    // Whether we are presenting or dismissing
    let isAppearing: Bool

    // The view controller that is not the shade
    weak var presentingVC: UIViewController?

    // The view controller that is the shade
    weak var presentedVC: UIViewController?

    // The delegate will vend the animator
    weak var transitionDelegate: UIViewControllerTransitioningDelegate?
    
    // Feedback generator for haptics on collisions
    let impactFeedbackGenerator = UIImpactFeedbackGenerator(style: .light)
    
    // The context given to the animator at the start of the transition
    var transitionContext: UIViewControllerContextTransitioning?
    
    // Time limit of the dynamic part of the animation
    var finishTime: TimeInterval = 4.0
    
    // The Pan Gesture that drives the transition. Not using EdgePan because triggers Notifications screen
    lazy var pan: UIPanGestureRecognizer =
    {
        let pan = UIPanGestureRecognizer(target: self, action: #selector(self.handlePan(sender:)))
        return pan
    }()
    
    // The dynamic animator that we add `ShadeAnimator` to
    lazy var animator: UIDynamicAnimator! =
    {
        let animator = UIDynamicAnimator(referenceView: self.transitionContext!.containerView)
        return animator
    }()
    
    // init with all of our dependencies
    init(isAppearing: Bool, presentingVC: UIViewController, presentedVC: UIViewController, transitionDelegate: UIViewControllerTransitioningDelegate)
    {
        self.isAppearing = isAppearing
        self.presentingVC = presentingVC
        self.presentedVC = presentedVC
        self.transitionDelegate = transitionDelegate
        super.init()
        self.impactFeedbackGenerator.prepare()
        
        if isAppearing
        {
            self.presentingVC?.view.addGestureRecognizer(pan)
        }
        else
        {
            self.presentedVC?.view.addGestureRecognizer(pan)
        }
        
    }
    
    // Setup and moves shade view controller to just above screen if appearing
    func setupViewsForTransition(with transitionContext: UIViewControllerContextTransitioning)
    {
        // Get relevant views and view controllers from transitionContext
        guard let fromVC = transitionContext.viewController(forKey: .from),
            let toVC = transitionContext.viewController(forKey: .to),
            let toView = toVC.view else { return }
        
        let containerView = transitionContext.containerView
        
        // Hold refrence to transitionContext to notify it of completion
        self.transitionContext = transitionContext
        if isAppearing
        {
            // Position toView  just off-screen
            let fromViewInitialFrame = transitionContext.initialFrame(for: fromVC)
            var toViewInitialFrame = toView.frame
            toViewInitialFrame.origin.y -= toViewInitialFrame.height
            toViewInitialFrame.origin.x = fromViewInitialFrame.width * 0.5 - toViewInitialFrame.width * 0.5
            toView.frame = toViewInitialFrame
            
            containerView.addSubview(toView)
        }
        else
        {
            fromVC.view.addGestureRecognizer(pan)
        }
    }
    
    // Handles the entire interaction from presenting/dismissing to completion
    func handlePan(sender: UIPanGestureRecognizer)
    {
        let location = sender.location(in: transitionContext?.containerView)
        let velocity = sender.velocity(in: transitionContext?.containerView)
        let fromVC = transitionContext?.viewController(forKey: .from)
        let toVC = transitionContext?.viewController(forKey: .to)
        
        let touchStartHeight: CGFloat = 90.0
        let touchLocationFromBottom: CGFloat = 20.0
        
        switch sender.state
        {
        case .began:
            let beginLocation = sender.location(in: sender.view)
            if isAppearing
            {
                guard beginLocation.y <= touchStartHeight,
                      let presentedVC = self.presentedVC else { break }
                presentedVC.modalPresentationStyle = .custom
                presentedVC.transitioningDelegate = transitionDelegate
                presentingVC?.present(presentedVC, animated: true)
            }
            else
            {
                guard beginLocation.y >= (sender.view?.frame.height ?? 0.0) - touchStartHeight else { break }
                presentedVC?.dismiss(animated: true)
            }
        case .changed:
            guard let view = isAppearing ? toVC?.view : fromVC?.view else { return }
            UIView.animate(withDuration: 0.2)
            {
                view.frame.origin.y = location.y - view.bounds.height + touchLocationFromBottom
            }
            
            transitionContext?.updateInteractiveTransition(view.frame.maxY / view.frame.height
            )
        case .ended, .cancelled:
            guard let view = isAppearing ? toVC?.view : fromVC?.view else { return }
            let isCancelled = isAppearing ? (velocity.y < 0.5 || view.center.y < 0.0) : (velocity.y > 0.5 || view.center.y > 0.0)
            addAttachmentBehavior(with: view, isCancelled: isCancelled)
            addCollisionBehavior(with: view)
            addItemBehavior(with: view)
            
            animator.addBehavior(self)
            animator.delegate = self
            
            self.action =
            { [weak self] in
                guard let strongSelf = self else { return }
                if strongSelf.animator.elapsedTime > strongSelf.finishTime
                {
                    strongSelf.animator.removeAllBehaviors()
                }
                else
                {
                    strongSelf.transitionContext?.updateInteractiveTransition(view.frame.maxY / view.frame.height
                    )
                }
            }
        default:
            break
        }
    }
    
    // Add collision behavior that causes bounce when finished
    func addCollisionBehavior(with view: UIView)
    {
        let collisionBehavior = UICollisionBehavior(items: [view])
        let insets = UIEdgeInsets(top: -view.bounds.height, left: 0.0, bottom: 0.0, right: 0.0)
        collisionBehavior.setTranslatesReferenceBoundsIntoBoundary(with: insets)
        collisionBehavior.collisionDelegate = self
        self.addChildBehavior(collisionBehavior)
    }
    
    // Add attachment behavior that pulls shade either to top or bottom
    func addAttachmentBehavior(with view: UIView, isCancelled: Bool)
    {
        let anchor: CGPoint
        switch (isAppearing, isCancelled)
        {
        case (true, true), (false, false):
            anchor = CGPoint(x: view.center.x, y: -view.frame.height)
        case (true, false), (false, true):
            anchor = CGPoint(x: view.center.x, y: view.frame.height)
        }
        let attachmentBehavior = UIAttachmentBehavior(item: view, attachedToAnchor: anchor)
        attachmentBehavior.damping = 0.1
        attachmentBehavior.frequency = 3.0
        attachmentBehavior.length = 0.5 * view.frame.height
        self.addChildBehavior(attachmentBehavior)
    }
    
    // Makes view more bouncy 
    func addItemBehavior(with view: UIView)
    {
        let itemBehavior = UIDynamicItemBehavior(items: [view])
        itemBehavior.allowsRotation = false
        itemBehavior.elasticity = 0.6
        self.addChildBehavior(itemBehavior)
    }
    
}
extension ShadeAnimator: UIDynamicAnimatorDelegate
{
    // Determines transition has ended
    func dynamicAnimatorDidPause(_ animator: UIDynamicAnimator)
    {
        guard let transitionContext = self.transitionContext else { return }
        let fromVC = transitionContext.viewController(forKey: .from)
        let toVC = transitionContext.viewController(forKey: .to)
        guard let view = isAppearing ? toVC?.view : fromVC?.view else { return }
        switch (view.center.y < 0.0, isAppearing)
        {
        case (true, true), (true, false):
            view.removeFromSuperview()
            transitionContext.finishInteractiveTransition()
            transitionContext.completeTransition(!isAppearing)
        case (false, true):
            toVC?.view.frame = transitionContext.finalFrame(for: toVC!)
            transitionContext.finishInteractiveTransition()
            transitionContext.completeTransition(true)
        case (false, false):
            fromVC?.view.frame = transitionContext.initialFrame(for: fromVC!)
            transitionContext.cancelInteractiveTransition()
            transitionContext.completeTransition(false)
        }
        childBehaviors.forEach { removeChildBehavior($0) }
        animator.removeAllBehaviors()
        self.animator = nil
        self.transitionContext = nil
    }
}
extension ShadeAnimator: UICollisionBehaviorDelegate
{
    // Triggers haptics
    func collisionBehavior(_ behavior: UICollisionBehavior, beganContactFor item: UIDynamicItem, withBoundaryIdentifier identifier: NSCopying?, at p: CGPoint)
    {
        guard p.y > 0.0 else { return }
        impactFeedbackGenerator.impactOccurred()
    }
}
extension ShadeAnimator: UIViewControllerInteractiveTransitioning
{
    // Starts transition
    func startInteractiveTransition(_ transitionContext: UIViewControllerContextTransitioning)
    {
        setupViewsForTransition(with: transitionContext)
    }
}

Cel C

@interface ShadeAnimator() <UIDynamicAnimatorDelegate, UICollisionBehaviorDelegate>
@property (nonatomic, assign) BOOL isAppearing;
@property (nonatomic, weak) UIViewController *presentingVC;
@property (nonatomic, weak) UIViewController *presentedVC;
@property (nonatomic, weak) NSObject<UIViewControllerTransitioningDelegate> *transitionDelegate;
@property (nonatomic, strong) UIImpactFeedbackGenerator *impactFeedbackGenerator;
@property (nonatomic, strong) id<UIViewControllerContextTransitioning> transitionContext;
@property (nonatomic, assign) NSTimeInterval finishTime;
@property (nonatomic, strong) UIPanGestureRecognizer *pan;
@property (nonatomic, strong) UIDynamicAnimator *animator;
@end

@implementation ShadeAnimator

- (instancetype)initWithIsAppearing:(BOOL)isAppearing presentingVC:(UIViewController *)presentingVC presentedVC:(UIViewController *)presentedVC transitionDelegate:(id<UIViewControllerTransitioningDelegate>)transitionDelegate
{
    self = [super init];
    if (self)
    {
        _isAppearing = isAppearing;
        _presentingVC = presentingVC;
        _presentedVC = presentedVC;
        _transitionDelegate = transitionDelegate;
        _impactFeedbackGenerator = [[UIImpactFeedbackGenerator alloc]initWithStyle:UIImpactFeedbackStyleLight];
        [_impactFeedbackGenerator prepare];
        if (_isAppearing)
        {
            [_presentingVC.view addGestureRecognizer:self.pan];
        }
        else
        {
            [_presentedVC.view addGestureRecognizer:self.pan];
        }
    }
    return self;
}

#pragma mark - Lazy Init
- (UIPanGestureRecognizer *)pan
{
    if (!_pan)
    {
        _pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(handlePan:)];
    }
    return _pan;
}

- (UIDynamicAnimator *)animator
{
    if (!_animator)
    {
        _animator = [[UIDynamicAnimator alloc]initWithReferenceView:self.transitionContext.containerView];
    }
    return _animator;
}

#pragma mark - Setup
- (void)setupViewForTransitionWithContext:(id<UIViewControllerContextTransitioning>)transitionContext
{
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIView *toView = toVC.view;
    UIView *containerView = transitionContext.containerView;
    self.transitionContext = transitionContext;
    if (self.isAppearing)
    {
        CGRect fromViewInitialFrame = [transitionContext initialFrameForViewController:fromVC];
        CGRect toViewInitialFrame = toView.frame;
        toViewInitialFrame.origin.y -= CGRectGetHeight(toViewInitialFrame);
        toViewInitialFrame.origin.x = CGRectGetWidth(fromViewInitialFrame) * 0.5 - CGRectGetWidth(toViewInitialFrame) * 0.5;
        
        [containerView addSubview:toView];
    }
    else
    {
        [fromVC.view addGestureRecognizer:self.pan];
    }
}

#pragma mark - Gesture
- (void)handlePan:(UIPanGestureRecognizer *)sender
{
    CGPoint location = [sender locationInView:self.transitionContext.containerView];
    CGPoint velocity = [sender velocityInView:self.transitionContext.containerView];
    UIViewController *fromVC = [self.transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [self.transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    
    CGFloat touchStartHeight = 90.0;
    CGFloat touchLocationFromBottom = 20.0;
    
    if (sender.state == UIGestureRecognizerStateBegan)
    {
        CGPoint beginLocation = [sender locationInView:sender.view];
        if (self.isAppearing)
        {
            if (beginLocation.y <= touchStartHeight)
            {
                self.presentedVC.modalPresentationStyle = UIModalPresentationCustom;
                self.presentedVC.transitioningDelegate = self.transitionDelegate;
                [self.presentingVC presentViewController:self.presentedVC animated:YES completion:nil];
            }
        }
        else
        {
            if (beginLocation.y >= [sender locationInView:sender.view].y - touchStartHeight)
            {
                [self.presentedVC dismissViewControllerAnimated:true completion:nil];
            }
        }
    }
    else if (sender.state == UIGestureRecognizerStateChanged)
    {
        UIView *view = self.isAppearing ? toVC.view : fromVC.view;
        [UIView animateWithDuration:0.2 animations:^{
            CGRect frame = view.frame;
            frame.origin.y = location.y - CGRectGetHeight(view.bounds) + touchLocationFromBottom;
            view.frame = frame;
        }];
        [self.transitionContext updateInteractiveTransition:CGRectGetMaxY(view.frame) / CGRectGetHeight(view.frame)];
    }
    else if (sender.state == UIGestureRecognizerStateEnded || sender.state == UIGestureRecognizerStateCancelled)
    {
        UIView *view = self.isAppearing ? toVC.view : fromVC.view;
        BOOL isCancelled = self.isAppearing ? (velocity.y < 0.5 || view.center.y < 0.0) : (velocity.y > 0.5 || view.center.y > 0.0);
        [self addAttachmentBehaviorWithView:view isCancelled:isCancelled];
        [self addCollisionBehaviorWithView:view];
        [self addItemBehaviorWithView:view];
        
        [self.animator addBehavior:self];
        self.animator.delegate = self;
        
        __weak ShadeAnimator *weakSelf = self;
        self.action =
        ^{
            if (weakSelf.animator.elapsedTime > weakSelf.finishTime)
            {
                [weakSelf.animator removeAllBehaviors];
            }
            else
            {
                [weakSelf.transitionContext updateInteractiveTransition:CGRectGetMaxY(view.frame) / CGRectGetHeight(view.frame)];
            }
        };
    }
}

#pragma mark - UIViewControllerInteractiveTransitioning
- (void)startInteractiveTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    [self setupViewForTransitionWithContext:transitionContext];
}

#pragma mark - Behaviors
- (void)addCollisionBehaviorWithView:(UIView *)view
{
    UICollisionBehavior *collisionBehavior = [[UICollisionBehavior alloc]initWithItems:@[view]];
    UIEdgeInsets insets = UIEdgeInsetsMake(-CGRectGetHeight(view.bounds), 0.0, 0.0, 0.0);
    [collisionBehavior setTranslatesReferenceBoundsIntoBoundaryWithInsets:insets];
    collisionBehavior.collisionDelegate = self;
    [self addChildBehavior:collisionBehavior];
}

- (void)addItemBehaviorWithView:(UIView *)view
{
    UIDynamicItemBehavior *itemBehavior = [[UIDynamicItemBehavior alloc]initWithItems:@[view]];
    itemBehavior.allowsRotation = NO;
    itemBehavior.elasticity = 0.6;
    [self addChildBehavior:itemBehavior];
}

- (void)addAttachmentBehaviorWithView:(UIView *)view isCancelled:(BOOL)isCancelled
{
    CGPoint anchor;
    if ((self.isAppearing && isCancelled) || (!self.isAppearing && isCancelled))
    {
        anchor = CGPointMake(view.center.x, -CGRectGetHeight(view.frame));
    }
    else
    {
        anchor = CGPointMake(view.center.x, -CGRectGetHeight(view.frame));
    }
    UIAttachmentBehavior *attachmentBehavior = [[UIAttachmentBehavior alloc]initWithItem:view attachedToAnchor:anchor];
    attachmentBehavior.damping = 0.1;
    attachmentBehavior.frequency = 3.0;
    attachmentBehavior.length = 0.5 * CGRectGetHeight(view.frame);
    [self addChildBehavior:attachmentBehavior];
}

#pragma mark - UICollisionBehaviorDelegate
- (void)collisionBehavior:(UICollisionBehavior *)behavior beganContactForItem:(id<UIDynamicItem>)item withBoundaryIdentifier:(id<NSCopying>)identifier atPoint:(CGPoint)p
{
    if (p.y > 0.0)
    {
        [self.impactFeedbackGenerator impactOccurred];
    }
}

#pragma mark - UIDynamicAnimatorDelegate
- (void)dynamicAnimatorDidPause:(UIDynamicAnimator *)animator
{
    UIViewController *fromVC = [self.transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [self.transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIView *view = self.isAppearing ? toVC.view : fromVC.view;
    if (view.center.y < 0.0 && (self.isAppearing ||  !self.isAppearing))
    {
        [view removeFromSuperview];
        [self.transitionContext finishInteractiveTransition];
        [self.transitionContext completeTransition:!self.isAppearing];
    }
    else if (view.center.y >= 0.0 && self.isAppearing)
    {
        toVC.view.frame = [self.transitionContext finalFrameForViewController:toVC];
        [self.transitionContext finishInteractiveTransition];
        [self.transitionContext completeTransition:YES];
    }
    else
    {
        fromVC.view.frame = [self.transitionContext initialFrameForViewController:fromVC];
        [self.transitionContext cancelInteractiveTransition];
        [self.transitionContext completeTransition:NO];
    }
    for (UIDynamicBehavior *behavior in self.childBehaviors)
    {
        [self removeChildBehavior:behavior];
    }
    [animator removeAllBehaviors];
    self.animator = nil;
    self.transitionContext = nil;
}

@end

Animator uruchamia początek przejścia, gdy rozpoczyna się gest panoramy. I po prostu przesuwa widok, gdy zmienia się gest. Ale kiedy gest się kończy, to wtedy UIDynamicBehaviors określa, czy przejście powinno zostać zakończone, czy anulowane. W tym celu wykorzystuje zachowanie załącznika i kolizji. Aby uzyskać więcej informacji, zobacz sesję WWDC 2013 „Zaawansowane techniki z UIKit Dynamics .

Mapa Dynamiczna animacja Zmiany pozycji w granicach

Ten przykład pokazuje, jak dostosować protokół UIDynamicItem do mapowania zmian pozycji widoku dynamicznie animowanego do zmian granic, aby utworzyć przycisk UIButton który rozszerza się i kurczy w sposób elastyczny.

Aby rozpocząć, musimy utworzyć nowy protokół, który implementuje UIDynamicItem ale który ma także ustawialną i gettable właściwość bounds .

Szybki

protocol ResizableDynamicItem: UIDynamicItem
{
    var bounds: CGRect { set get }
}
extension UIView: ResizableDynamicItem {}

Cel C

@protocol ResizableDynamicItem <UIDynamicItem>
@property (nonatomic, readwrite) CGRect bounds;
@end

Następnie utworzymy obiekt otoki, który UIDynamicItem ale UIDynamicItem zmiany środka na szerokość i wysokość elementu. Zapewnimy również przejścia dla bounds i transform przedmiotu bazowego. Spowoduje to wszelkie zmiany, które animator dynamiczny wprowadza do środka x, a wartości y elementu bazowego zostaną zastosowane do szerokości i wysokości elementów.

Szybki

final class PositionToBoundsMapping: NSObject, UIDynamicItem
{
    var target: ResizableDynamicItem
    
    init(target: ResizableDynamicItem)
    {
        self.target = target
        super.init()
    }
    
    var bounds: CGRect
    {
        get
        {
            return self.target.bounds
        }
    }
    
    var center: CGPoint
    {
        get
        {
            return CGPoint(x: self.target.bounds.width, y: self.target.bounds.height)
        }
        
        set
        {
            self.target.bounds = CGRect(x: 0.0, y: 0.0, width: newValue.x, height: newValue.y)
        }
    }
    
    var transform: CGAffineTransform
    {
        get
        {
            return self.target.transform
        }
        
        set
        {
            self.target.transform = newValue
        }
    }
}

Cel C

@interface PositionToBoundsMapping ()
@property (nonatomic, strong) id<ResizableDynamicItem> target;
@end

@implementation PositionToBoundsMapping

- (instancetype)initWithTarget:(id<ResizableDynamicItem>)target
{
    self = [super init];
    if (self)
    {
        _target = target;
    }
    return self;
}

- (CGRect)bounds
{
    return self.target.bounds;
}

- (CGPoint)center
{
    return CGPointMake(self.target.bounds.size.width, self.target.bounds.size.height);
}

- (void)setCenter:(CGPoint)center
{
    self.target.bounds = CGRectMake(0, 0, center.x, center.y);
}

- (CGAffineTransform)transform
{
    return self.target.transform;
}

- (void)setTransform:(CGAffineTransform)transform
{
    self.target.transform = transform;
}

@end

Wreszcie utworzymy UIViewController który będzie miał przycisk. Po naciśnięciu przycisku utworzymy PositionToBoundsMapping z przyciskiem jako zawiniętym elementem dynamicznym. Tworzymy UIAttachmentBehavior do jego aktualnej pozycji, a następnie dodajemy do niego natychmiastowe UIPushBehavior . Ponieważ jednak mapowaliśmy, zmienia swoje granice, przycisk nie porusza się, a raczej rośnie i kurczy się.

Szybki

final class ViewController: UIViewController
{
    lazy var button: UIButton =
    {
        let button = UIButton(frame: CGRect(x: 0.0, y: 0.0, width: 300.0, height: 200.0))
        button.backgroundColor = .red
        button.layer.cornerRadius = 15.0
        button.setTitle("Tap Me", for: .normal)
        self.view.addSubview(button)
        return button
    }()
    
    var buttonBounds = CGRect.zero
    var animator: UIDynamicAnimator?
    
    override func viewDidLoad() 
    {
        super.viewDidLoad()
        view.backgroundColor = .white
        button.addTarget(self, action: #selector(self.didPressButton(sender:)), for: .touchUpInside)
        buttonBounds = button.bounds
    }
    
    override func viewDidLayoutSubviews() 
    {
        super.viewDidLayoutSubviews()
        button.center = view.center
    }
    
    func didPressButton(sender: UIButton)
    {
        // Reset bounds so if button is press twice in a row, previous changes don't propogate
        button.bounds = buttonBounds
        let animator = UIDynamicAnimator(referenceView: view)
        
        // Create mapping
        let buttonBoundsDynamicItem = PositionToBoundsMapping(target: button)
        
        // Add Attachment behavior
        let attachmentBehavior = UIAttachmentBehavior(item: buttonBoundsDynamicItem, attachedToAnchor: buttonBoundsDynamicItem.center)
        
        // Higher frequency faster oscillation
        attachmentBehavior.frequency = 2.0
        
        // Lower damping longer oscillation lasts
        attachmentBehavior.damping = 0.1
        animator.addBehavior(attachmentBehavior)
        
        let pushBehavior = UIPushBehavior(items: [buttonBoundsDynamicItem], mode: .instantaneous)
        
        // Change angle to determine how much height/ width should change 45° means heigh:width is 1:1
        pushBehavior.angle = .pi / 4.0
        
        // Larger magnitude means bigger change
        pushBehavior.magnitude = 30.0
        animator.addBehavior(pushBehavior)
        pushBehavior.active = true
        
        // Hold refrence so animator is not released
        self.animator = animator
    }
}

Cel C

@interface ViewController ()
@property (nonatomic, strong) UIButton *button;
@property (nonatomic, assign) CGRect buttonBounds;
@property (nonatomic, strong) UIDynamicAnimator *animator;
@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    [self.button addTarget:self action:@selector(didTapButton:) forControlEvents:UIControlEventTouchUpInside];
    self.buttonBounds = self.button.bounds;
}

- (void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];
    self.button.center = self.view.center;
}

- (UIButton *)button
{
    if (!_button)
    {
        _button = [[UIButton alloc]initWithFrame:CGRectMake(0.0, 0.0, 200.0, 200.0)];
        _button.backgroundColor = [UIColor redColor];
        _button.layer.cornerRadius = 15.0;
        [_button setTitle:@"Tap Me" forState:UIControlStateNormal];
        [self.view addSubview:_button];
    }
    return _button;
}

- (void)didTapButton:(id)sender
{
    self.button.bounds = self.buttonBounds;
    UIDynamicAnimator *animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];
    PositionToBoundsMapping *buttonBoundsDynamicItem = [[PositionToBoundsMapping alloc]initWithTarget:sender];
    UIAttachmentBehavior *attachmentBehavior = [[UIAttachmentBehavior alloc]initWithItem:buttonBoundsDynamicItem attachedToAnchor:buttonBoundsDynamicItem.center];
    [attachmentBehavior setFrequency:2.0];
    [attachmentBehavior setDamping:0.3];
    [animator addBehavior:attachmentBehavior];
    
    UIPushBehavior *pushBehavior = [[UIPushBehavior alloc] initWithItems:@[buttonBoundsDynamicItem] mode:UIPushBehaviorModeInstantaneous];
    pushBehavior.angle = M_PI_4;
    pushBehavior.magnitude = 2.0;
    [animator addBehavior:pushBehavior];
    
    [pushBehavior setActive:TRUE];
    
    self.animator = animator;
}

@end

Aby uzyskać więcej informacji, zobacz Katalog Dynamiki UIKit