How to pause and resume UIView.animateWithDuration - ios

Question

I have an image, I animate it with this code, in viewDidAppear:
UIView.animateWithDuration(10.5, delay:0.0, options: [], animations:{
self.myImage.transform = CGAffineTransformMakeTranslation(0.0, 200)
}, completion: nil)
I want to pause the animation when I tap myPauseButton, and resume the animation if I tap it again.

Answer 1

2 functions to pause and resume animation, I take from here and convert to Swift.
func pauseLayer(layer: CALayer) {
let pausedTime: CFTimeInterval = layer.convertTime(CACurrentMediaTime(), from: nil)
layer.speed = 0.0
layer.timeOffset = pausedTime
}
func resumeLayer(layer: CALayer) {
let pausedTime: CFTimeInterval = layer.timeOffset
layer.speed = 1.0
layer.timeOffset = 0.0
layer.beginTime = 0.0
let timeSincePause: CFTimeInterval = layer.convertTime(CACurrentMediaTime(), from: nil) - pausedTime
layer.beginTime = timeSincePause
}
I have a button to pause or resume the animation which is initiated in viewDidLoad:
var pause = false
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
UIView.animate(withDuration: 10.5) {
self.image.transform = CGAffineTransformMakeTranslation(0.0, 200)
}
}
#IBAction func changeState() {
let layer = image.layer
pause = !pause
if pause {
pauseLayer(layer)
} else {
resumeLayer(layer)
}
}

Answer 2

Here is Swift 3 version of that answer + I moved those function to an extension
extension CALayer {
func pause() {
let pausedTime: CFTimeInterval = self.convertTime(CACurrentMediaTime(), from: nil)
self.speed = 0.0
self.timeOffset = pausedTime
}
func resume() {
let pausedTime: CFTimeInterval = self.timeOffset
self.speed = 1.0
self.timeOffset = 0.0
self.beginTime = 0.0
let timeSincePause: CFTimeInterval = self.convertTime(CACurrentMediaTime(), from: nil) - pausedTime
self.beginTime = timeSincePause
}
}

Answer 3

Since iOS 10 provides UIViewPropertyAnimator you can solve your problem easier.
Declare these properties in your controller:
var animationPaused = false
lazy var animator: UIViewPropertyAnimator = UIViewPropertyAnimator(duration: 10.5, curve: .easeInOut, animations: {
self.myImage.transform = CGAffineTransform(translationX: 0.0, y: 200)
})
Add the following code to the tap handler of myPauseButton:
if self.animator.state == .active { // Don't start or pause the animation when it's finished
self.animationPaused = !self.animationPaused
self.animationPaused ? self.animator.pauseAnimation() : self.animator.startAnimation()
}
Start the animation in viewDidAppear(_ animated: Bool) with these lines of code:
self.animationPaused = false
self.animator.startAnimation()