CATransition type fade seem broken-CodePudding

When working on this question, I notice that maybe fade of CATransitionType in CATransition not working or broken. The rest of CATransitionType: moveIn, push, reveal works correctly.

I'm working on iPhone 13, iOS 16.0.

Code of the transition

extension CALayer {
    func makeFadeTransition() {
        let transition = CATransition()
        transition.timingFunction = CAMediaTimingFunction(name: .easeInEaseOut)
        transition.duration = 0.5
        transition.type = .fade
        self.add(transition, forKey: nil)
    }
}

Usage

self.customView.layer.makeFadeTransition()

I know that we can switch to using UIView.animate combine with alpha to change opacity instead

UIView.animate(withDuration: 0.15, animations: {
    self.customView.alpha = 0.0
})

or using CABasicAnimation

extension CALayer {
    func makeFadeTransition() {
        let transition = CABasicAnimation(keyPath: "opacity")
        transition.timingFunction = CAMediaTimingFunction(name: .easeInEaseOut)
        transition.duration = 0.5
        transition.fromValue = 1.0
        transition.toValue = 0.0
        self.add(transition, forKey: nil)
    }
}

But again, is CATransitionType type fade broken or I'm wrong at something. Thanks in advanced.

CodePudding user response：

You have to do something to change the layer...

For example, to fade-out / fade-in, we could do this:

extension CALayer {
    func makeFadeTransition() {

        let transition = CATransition()
        transition.timingFunction = CAMediaTimingFunction(name: .easeInEaseOut)
        // let's use duration of 2.5 to make it more obvious
        transition.duration = 2.5
        transition.type = .fade
        
        // change the layer... opacity, backgroundColor, frame, etc
        
        // fade transition doesn't like opacity of 0.0, so we'll use 0.01
        self.opacity = self.opacity == 1.0 ? 0.01 : 1.0
        
        // or, for example,
        // "shrink" the layer by 20-points
        //self.frame = self.frame.insetBy(dx: 20.0, dy: 20.0)
    
        self.add(transition, forKey: nil)
        
    }
}