Pause and Resume UIViewAnimation when app goes to background

Question

I am animating a view and I want to pause it and resume it.

Using an apple guide I created a CALayer Extension

extension CALayer {

    func pause() {
        var pauseTime = self.convertTime(CACurrentMediaTime(), fromLayer: nil)
        self.speed = 0.0
        self.timeOffset = pauseTime
    }

    func resume() {
        var pausedTime = self.timeOffset
        self.speed = 1.0
        self.timeOffset = 0.0
        self.beginTime = 0.0
        var timeSincePause = self.convertTime(CACurrentMediaTime(), toLayer: nil) - pausedTime

        self.beginTime = timeSincePause
    }
}

This code is working perfectly except when that app goes to background. When I bring the App back to foreground animations is finished (even if the time is not pass) and it is not starting again when I click resume.

Ok. I tried animating CALayer but I have the same problem.

extension CALayer {

   func animateY(newY:CGFloat,time:NSTimeInterval,completion:()->Void){
    CATransaction.begin()
    CATransaction.setCompletionBlock(completion)
    let animation = CABasicAnimation(keyPath: "position.y")
    animation.fromValue = self.position.y
    animation.toValue  = newY
    animation.duration = time
    animation.delegate = self
    animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
    animation.removedOnCompletion = false // don't remove after finishing
    self.position.y = newY
    self.addAnimation(animation, forKey: "position.y")
    CATransaction.flush()

  }
}

Have you tried setting `removedOnCompletion=NO;` for you animation. That should stop it being removed. — Rory McKinnel, Jun 02 '15 at 13:42
You can also add an observer for the notification event `UIApplicationDidBecomeActiveNotification` inside which you can rejig your animation. You can treat this like `viewWillAppear` as it is not called on resume from background. — Rory McKinnel, Jun 02 '15 at 13:55
there's a ton of duplicate questions on this, including the answer to "Restoring animation where it left off when app resumes from background". See http://stackoverflow.com/questions/7568567/restoring-animation-where-it-left-off-when-app-resumes-from-background/7983292#7983292 — Max MacLeod, Jun 03 '15 at 08:25
You haven`t noticed that i tried the method in the answer and is not working for me. :) — Christos Chadjikyriacou, Jun 03 '15 at 08:35

score 0 · Answer 1 · edited May 23 '17 at 11:45

0

I recommend using CABasicAnimation. Your resume/pause methods should be fine, since they are from this answer. You should try using Core Animation instead of UIViewAnimation and then the resume/pause will work.

Then you can register for the two notifications UIApplicationWillEnterForegroundNotification and UIApplicationDidEnterBackgroundNotification to have full control over the pause/resume actions.

edited May 23 '17 at 11:45

Community

1
1

answered Jun 02 '15 at 13:42

Teo

3,394
11
43
73

That is the same code as the question code, just not implemented as a CALayer extension. – Rory McKinnel Jun 02 '15 at 13:51
Yeah, but he is using UIViewAnimation instead of Core Animation. That is why I think his code has no effect, because it should be used with a layer animation. – Teo Jun 02 '15 at 13:57

Pause and Resume UIViewAnimation when app goes to background

1 Answers1

Linked