Subclassing UIButton and overriding touch events - not working

Question

I need a scale spring animation for all my buttons in a project. So i subclassed UIButton and override touch event functions.

import UIKit

class UIAnimatedButton: UIButton {

override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {

    UIView.animateWithDuration(0.1, animations: { () -> Void in
        self.transform = CGAffineTransformMakeScale(0.8, 0.8)

    })
    super.touchesBegan(touches, withEvent: event)

}

override func touchesCancelled(touches: Set<NSObject>!, withEvent event: UIEvent!) {


    UIView.animateWithDuration(0.5,
        delay: 0,
        usingSpringWithDamping: 0.2,
        initialSpringVelocity: 6.0,
        options: UIViewAnimationOptions.AllowUserInteraction,
        animations: { () -> Void in
            self.transform = CGAffineTransformIdentity
    }) { (Bool) -> Void in
        super.touchesCancelled(touches, withEvent: event)
    }

}


override func touchesEnded(touches: Set<NSObject>, withEvent event: UIEvent) {

    UIView.animateWithDuration(0.5,
        delay: 0,
        usingSpringWithDamping: 0.2,
        initialSpringVelocity: 6.0,
        options: UIViewAnimationOptions.AllowUserInteraction,
        animations: { () -> Void in
            self.transform = CGAffineTransformIdentity
        }) { (Bool) -> Void in
            super.touchesEnded(touches, withEvent: event)
    }
  }
} 

this works great in a fast tap but when i touch the button for a long time (1-2 seconds) i don't get a touch up inside action event. when i switch it back to a regular UIButton everything works fine.

Any ideas why that happens?

Answer 1

Not sure exactly why yet, but you need to call super.touchesEnded(touches, with: event) outside the animation

So (Swift 5)

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    UIView.animate(withDuration: 0.5,
        delay: 0,
        usingSpringWithDamping: 0.2,
        initialSpringVelocity: 6.0,
        options: UIView.AnimationOptions.allowUserInteraction,
        animations: { () -> Void in
            self.transform = CGAffineTransform.identity
        }) { (Bool) -> Void in
    }
    super.touchesEnded(touches, with: event)
}

Answer 2

This is an approach that works as of Swift 5, so UIButton subclass can intercept its button push, and forward the registered target/action listeners external to the button class:

1. In the UIView superview of the subclassed button:

    button.addTarget(self, action: #selector(buttonPushed), 
       for: .primaryActionTriggered)
   

2. In button subclass, detect button press by adding this to init() method:

    let tapGestureRecognizer = UITapGestureRecognizer(target: self, 
           action: #selector(buttonPressed))
    tapGestureRecognizer.numberOfTapsRequired    = 1;
    tapGestureRecognizer.numberOfTouchesRequired = 1;
    self.addGestureRecognizer(tapGestureRecognizer)
   

3. Trap button press inside the subclass with a handler:

    @objc func buttonPressed() {
       // .
       // . (do whatever subclass needs to)
       // .
       self.sendActions(for: .primaryActionTriggered)
    }
   

Without sendActions, the gestureRecognizer that was added in init will prevent the event from being propagated to the consumers in the ResponderChain.