Back button starts a UIViewPropertyAnimator? - ios

Question

I have a ViewController with a camera for recording videos. On top there is a spinning circle to indicate that the video is being recorded. This is setup like so:
class CameraViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
private var animator: UIViewPropertyAnimator?
#objc func handleTap(_ gesture:UITapGestureRecognizer) {
if animator == nil {
createAnimation()
}
startRecording()
}
private func createAnimation() {
animator = UIViewPropertyAnimator.runningPropertyAnimator(withDuration: 4, delay: 0, options: [.curveLinear,.allowUserInteraction], animations: {
UIView.animateKeyframes(withDuration: 4, delay: 0, animations: {
UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 1.0 / 3.0) {
self.recordingSpinner.transform = .init(rotationAngle: .pi * 2 * 1 / 3)
}
UIView.addKeyframe(withRelativeStartTime: 1.0 / 3.0, relativeDuration: 1.0 / 3.0) {
self.recordingSpinner.transform = .init(rotationAngle: .pi * 2 * 2 / 3)
}
UIView.addKeyframe(withRelativeStartTime: 2.0 / 3.0, relativeDuration: 1.0 / 3.0) {
self.recordingSpinner.transform = .identity
}
})
}, completion: { [weak self] _ in
self?.createAnimation()
})
}
func startRecording() {
if movieOutput.isRecording == false {
animator?.startAnimation()
let connection = movieOutput.connection(with: AVMediaType.video)
if (connection?.isVideoOrientationSupported)! {
connection?.videoOrientation = currentVideoOrientation()
}
if (connection?.isVideoStabilizationSupported)! {
connection?.preferredVideoStabilizationMode = AVCaptureVideoStabilizationMode.auto
}
let device = activeInput.device
if (device.isSmoothAutoFocusSupported) {
do {
try device.lockForConfiguration()
device.isSmoothAutoFocusEnabled = false
device.unlockForConfiguration()
} catch {
print("Error setting configuration: \(error)")
}
}
let outputFileName = NSUUID().uuidString
let outputFilePath = (NSTemporaryDirectory() as NSString).appendingPathComponent((outputFileName as NSString).appendingPathExtension("mov")!)
movieOutput.startRecording(to: URL(fileURLWithPath: outputFilePath), recordingDelegate: self)
}
else {
stopRecording()
}
}
func stopRecording() {
if movieOutput.isRecording == true {
animator?.pauseAnimation()
movieOutput.stopRecording()
}
}
#IBAction func unwindToCamera(sender: UIStoryboardSegue) {
}
...
}
extension CameraViewController: AVCaptureFileOutputRecordingDelegate{
func fileOutput(_ output: AVCaptureFileOutput, didFinishRecordingTo outputFileURL: URL, from connections: [AVCaptureConnection], error: Error?) {
if (error != nil) {
print("Error recording movie: \(error!.localizedDescription)")
} else {
self.footageURL = outputFileURL as URL
//print(self.videoRecorded!)
self.performSegue(withIdentifier: "TrimFootage_Segue", sender: nil)
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?){
if segue.identifier == "TrimFootage_Segue" {
let controller = segue.destination as! TrimFootageViewController
controller.footageURL = self.footageURL
}
}
}
So it create an animator if it doesn't exist and then calls startRecording which starts the animation. then stopRecording stops it. Then when the video finishes recording to an output file, it segues to a newView controller. When I press back on that view controller it uses an unwind segue - unwindToCameraWithSender:
When I unwind and come back to the camera, the video is not recording, but the animation is playing. What could have caused this animation to start again? How can I prevent this?

Answer 1

I think the animation only being paused is the reason. In the stopRecording() method try
animator?.stopAnimation(true)
instead of
animator?.pauseAnimation()

Answer 2

So one thing I did to get around this, but not fix it is using the UIDynamicAnimator like so:
#objc func handleTap(_ gesture:UITapGestureRecognizer) {
startRecording()
if let rotate = rotate{
animator.removeBehavior(rotate)
self.rotate = nil
} else {
rotate = UIDynamicItemBehavior(items: [self.recordingSpinner])
rotate?.allowsRotation = true
rotate?.angularResistance = 0
rotate?.addAngularVelocity(1, for: self.recordingSpinner)
animator.addBehavior(rotate!)
}
}
taken from this answer: Proper way to stop an infinitely rotating image? and how does one implement removeAllAnimations?
Interestingly it seems not to start the rotation when I perform the segue though I'm not sure why. If anyone has thoughts on why I would love to hear them