Xamarin.Forms
Creando controles personalizados

Creando un botón personalizado

/// <summary>
/// Button with some additional options
/// </summary>
public class TurboButton : Button
{
    public static readonly BindableProperty StringDataProperty = BindableProperty.Create(
      propertyName: "StringData",
      returnType: typeof(string),
      declaringType: typeof(ButtonWithStorage),
      defaultValue: default(string));

    public static readonly BindableProperty IntDataProperty = BindableProperty.Create(
      propertyName: "IntData",
      returnType: typeof(int),
      declaringType: typeof(ButtonWithStorage),
      defaultValue: default(int));

    /// <summary>
    /// You can put here some string data
    /// </summary>
    public string StringData
    {
        get { return (string)GetValue(StringDataProperty); }
        set { SetValue(StringDataProperty, value); }
    }

    /// <summary>
    /// You can put here some int data
    /// </summary>
    public int IntData
    {
        get { return (int)GetValue(IntDataProperty); }
        set { SetValue(IntDataProperty, value); }
    }

    public TurboButton()
    {
        PropertyChanged += CheckIfPropertyLoaded;
    }

    /// <summary>
    /// Called when one of properties is changed
    /// </summary>
    private void CheckIfPropertyLoaded(object sender, PropertyChangedEventArgs e)
    {
        //example of using PropertyChanged
        if(e.PropertyName == "IntData")
        {
            //IntData is now changed, you can operate on updated value
        }
    }
}

Uso en XAML:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="SomeApp.Pages.SomeFolder.Example"
    xmlns:customControls="clr-namespace:SomeApp.CustomControls;assembly=SomeApp">
    <StackLayout>
        <customControls:TurboButton x:Name="exampleControl" IntData="2" StringData="Test" />
    </StackLayout>
</ContentPage>

Ahora, puedes usar tus propiedades en c #:

exampleControl.IntData

Tenga en cuenta que debe especificar dónde se ubica su clase TurboButton en su proyecto. Lo he hecho en esta línea:

xmlns:customControls="clr-namespace:SomeApp.CustomControls;assembly=SomeApp"

Puedes cambiar libremente "customControls" a otro nombre. Depende de usted cómo lo llamará.