iOS
NSPredicate

Syntaxis

• Predicaat Formaat String Substitions
  • Tekenreeksspecificaties in C-formaat:% d,% s,% f, enz
  • Objectvervanging:% @
  • Keypath-vervanging:% K
• Predicaat-vergelijkingsoperatoren
  • =, ==: linkerhand expressie is gelijk aan rechterhand expressie
  • > =, =>: Linkerhand uitdrukking is groter dan of gelijk aan rechterhand uitdrukking
  • <=, = <: Linkerhand expressie is kleiner dan of gelijk aan rechterhand expressie
  • >: Linkerhand uitdrukking is groter dan rechterhand uitdrukking
  • <: Linkerhand uitdrukking is minder dan rechterhand uitdrukking
  • ! =, <>: Linkerhand expressie is niet gelijk aan rechterhand expressie
  • TUSSEN: Linkeruitdrukking is tussen of gelijk aan een van de waarden in de rechteruitdrukking, die onder- en bovengrenzen aangeeft - bijvoorbeeld: TUSSEN {0, 5}
• Predicaat samengestelde operators
  • AND, &&: Logisch AND
  • OF, ||: Logische OF
  • NOT,!: Logisch NOT
• Predicaat String Vergelijking Operators
  • BEGINSWITH: linkerhanduitdrukking begint met rechterhanduitdrukking
  • ENDSWITH: linkerhanduitdrukking eindigt met rechterhanduitdrukking
  • BEVAT: Linkeruitdrukking bevat rechteruitdrukking
  • LIKE: expressie aan de linkerkant is gelijk aan expressie aan de rechterkant, met vervanging van jokertekens
    • *: Match nul of meer tekens
    • ?: Match één karakter

Een NSPredicate maken met predicateWithBlock

Doelstelling C

NSPredicate *predicate = [NSPredicate predicateWithBlock:^BOOL(id item, 
                                                               NSDictionary *bindings) {
    return [item isKindOfClass:[UILabel class]];
}];

Snel

let predicate = NSPredicate { (item, bindings) -> Bool in
    return item.isKindOfClass(UILabel.self)
}

In dit voorbeeld komt het predicaat overeen met items van de klasse UILabel .

Een NSPredicate maken met predicateWithFormat

Doelstelling C

NSPredicate *predicate = [NSPredicate predicateWithFormat: @"self[SIZE] = %d", 5)];

Snel

let predicate = NSPredicate(format: "self[SIZE] >= %d", 5)

In dit voorbeeld komt het predicaat overeen met items die arrays zijn met een lengte van ten minste 5.

Een NSP-certificaat maken met vervangingsvariabelen

Een NSPredicate kan substitutievariabelen gebruiken om waarden direct te binden.

Doelstelling C

NSPredicate *template = [NSPredicate predicateWithFormat: @"self BEGINSWITH $letter"];
NSDictionary *variables = @{ @"letter": @"r" };
NSPredicate *beginsWithR = [template predicateWithSubstitutionVariables: variables];

Snel

let template = NSPredicate(format: "self BEGINSWITH $letter")
let variables = ["letter": "r"]
let beginsWithR = template.predicateWithSubstitutionVariables(variables)

Het sjabloonpredikaat wordt niet gewijzigd door predicateWithSubstitutionVariables . In plaats daarvan wordt een kopie gemaakt en ontvangt die kopie de vervangingsvariabelen.

NSPredicate gebruiken om een array te filteren

Doelstelling C

NSArray *heroes = @[@"tracer", @"bastion", @"reaper", @"junkrat", @"roadhog"];

NSPredicate *template = [NSPredicate predicateWithFormat:@"self BEGINSWITH $letter"];

NSDictionary *beginsWithRVariables = @{ @"letter": @"r"};
NSPredicate *beginsWithR = [template predicateWithSubstitutionVariables: beginsWithRVariables];

NSArray *beginsWithRHeroes = [heroes filteredArrayUsingPredicate: beginsWithR];
// ["reaper", "roadhog"]

NSDictionary *beginsWithTVariables = @{ @"letter": @"t"};
NSPredicate *beginsWithT = [template predicateWithSubstitutionVarables: beginsWithTVariables];

NSArray *beginsWithTHeroes = [heroes filteredArrayUsingPredicate: beginsWithT];
// ["tracer"]

Snel

let heroes = ["tracer", "bastion", "reaper", "junkrat", "roadhog"]

let template = NSPredicate(format: "self BEGINSWITH $letter")

let beginsWithRVariables = ["letter": "r"]
let beginsWithR = template.predicateWithSubstitutionVariables(beginsWithRVariables)

let beginsWithRHeroes = heroes.filter { beginsWithR.evaluateWithObject($0) }
// ["reaper", "roadhog"]

let beginsWithTVariables = ["letter": "t"]
let beginsWithT = template.predicateWithSubstitutionVariables(beginsWithTVariables)

let beginsWithTHeroes = heroes.filter { beginsWithT.evaluateWithObject($0) }
// ["tracer"]

Formuliervalidatie met behulp van NSPredicate

NSString *emailRegex = @"[A-Z0-9a-z]([A-Z0-9a-z._-]{0,64})+[A-Z0-9a-z]+@[A-Z0-9a-z]+([A-Za-z0-9.-]{0,64})+([A-Z0-9a-z])+\\.[A-Za-z]{2,4}";    NSString *firstNameRegex = @"[0-9A-Za-z\"'-]{2,32}$";
NSString *firstNameRegex = @"[ 0-9A-Za-z]{2,32}$";
NSString *lastNameRegex = @"[0-9A-Za-z\"'-]{2,32}$";
NSString *mobileNumberRegEx = @"^[0-9]{10}$";
NSString *zipcodeRegEx = @"^[0-9]{5}$";
NSString *SSNRegEx = @"^\\d{3}-?\\d{2}-?\\d{4}$";
NSString *addressRegEx = @"^[ A-Za-z0-9]{2,32}$";
NSString *cityRegEx = @"^[ A-Za-z0-9]{2,25}$";
NSString *PINRegEx = @"^[0-9]{4}$";
NSString *driversLiscRegEx = @"^[0-9a-zA-Z]{5,20}$";

-(BOOL)validateEmail {
    //Email address field should give an error when the email address begins with ".","-","_" .
    NSPredicate *emailPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];   
    return ([emailPredicate evaluateWithObject:self.text] && self.text.length <= 64 && ([self.text rangeOfString:@".."].location == NSNotFound));
}

- (BOOL)validateFirstName {
    NSPredicate *firstNamePredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", firstNameRegex];
    return [firstNamePredicate evaluateWithObject:self.text];
}

- (BOOL)validateLastName {
    NSPredicate *lastNamePredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", lastNameRegex];
    return [lastNamePredicate evaluateWithObject:self.text];
}

- (BOOL)validateAlphaNumericMin2Max32 {
    NSPredicate *firstNamePredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", firstNameRegex];
    return [firstNamePredicate evaluateWithObject:self.text];
}

- (BOOL)validateMobileNumber {
    NSString *strippedMobileNumber =  [[[[self.text stringByReplacingOccurrencesOfString:@"(" withString:@""]
                                        stringByReplacingOccurrencesOfString:@")" withString:@""]
                                        stringByReplacingOccurrencesOfString:@"-" withString:@""]
                                        stringByReplacingOccurrencesOfString:@" " withString:@""];
    
    NSPredicate *mobileNumberPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", mobileNumberRegEx];
    
    return [mobileNumberPredicate evaluateWithObject:strippedMobileNumber];
}

- (BOOL)validateZipcode {
    NSPredicate *zipcodePredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", zipcodeRegEx];
    
    return [zipcodePredicate evaluateWithObject:self.text];
}

- (BOOL)validateSSN {
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", SSNRegEx];

return [predicate evaluateWithObject:self.text];
}

- (BOOL)validateAddress {
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", addressRegEx];
    
    return [predicate evaluateWithObject:self.text];
}

- (BOOL)validateCity {
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", cityRegEx];
    return [predicate evaluateWithObject:self.text];
}

- (BOOL)validatePIN {
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", PINRegEx];    
    return [predicate evaluateWithObject:self.text];
}
   - (BOOL)validateDriversLiscNumber {
    if([self.text length] > 20) {
        return NO;
    }
    NSPredicate *driversLiscPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", driversLiscRegEx];
    
    return [driversLiscPredicate evaluateWithObject:self.text];
}

NSP-certificaat met de voorwaarde `AND`,` OR` en `NOT`

Voorwaardelijk predicaat zal schoner en veiliger zijn door de NSCompoundPredicate klasse te gebruiken die basis booleaanse operatoren biedt voor de gegeven predicaten.

Doelstelling C

EN - Staat

  NSPredicate *predicate = [NSPredicate predicateWithFormat:@"samplePredicate"];
  NSPredicate *anotherPredicate = [NSPredicate predicateWithFormat:@"anotherPredicate"];
  NSPredicate *combinedPredicate = [NSCompoundPredicate andPredicateWithSubpredicates: @[predicate,anotherPredicate]];

OF - Staat

 NSPredicate *predicate = [NSPredicate predicateWithFormat:@"samplePredicate"];
 NSPredicate *anotherPredicate = [NSPredicate predicateWithFormat:@"anotherPredicate"];
 NSPredicate *combinedPredicate = [NSCompoundPredicate orPredicateWithSubpredicates: @[predicate,anotherPredicate]];

NIET - Staat

 NSPredicate *predicate = [NSPredicate predicateWithFormat:@"samplePredicate"];
 NSPredicate *anotherPredicate = [NSPredicate predicateWithFormat:@"anotherPredicate"];
 NSPredicate *combinedPredicate = [NSCompoundPredicate notPredicateWithSubpredicate: @[predicate,anotherPredicate]];