CODEWITHSUNDEEP
iosswiftuiimageviewuiviewanimation
Dani
Dani

Reputation: 3637

Image rotating animation speeds up while switching between view controllers?

I have an app where there's an UIImageView that's being rotated clockwise using UIView.animate like so: 

func startAnimation(targetView: UIView, duration: Double = 6)
{
    UIView.animate(withDuration: duration, delay: 0.0, options: .curveLinear, animations: {
        targetView.transform = targetView.transform.rotated(by: CGFloat(Double.pi))
    })
    { finished in
        self.startAnimation(targetView: targetView, duration: duration)
    }
}

This function is called in viewDidApear() only (main reason for that is because I have 2 more UIViewControllers that the user can go back and forth with.

I also have a stopAnimation() function that is called in viewWillDisappear(). Main goal is to stop the animation when the user is being presented with another view controller.

func stopAnimation()
{
    self.view.layer.removeAllAnimations()
    self.view.layoutIfNeeded()
}

Goal: The animation should be infinite while the user stays on the same view controller, but when they switch to another, the animation should stop and when they go back to that view controller the animation should start again with the same constant velocity.

Problem: For some reason each time you switch between another view controller and the view controller that has that animation, the animation is being sped up. I'm not sure what's causing that.

EDIT: Additional code as requested: 

override func viewDidAppear(_ animated: Bool)
{
    super.viewDidAppear(animated)
    startAnimation(targetView: logo)

}

Upvotes: 1

Views: 65

Answers (1)

torinpitchers
torinpitchers

Reputation: 1292

you need to reset the transform every time before you start animating. Otherwise it may well already be half way towards the end of the rotation. Hence taking a shorter time or further away = longer time. Also use .repeat instead of recursion.

func startAnimation(targetView: UIView, duration: Double = 6)
{
    targetView.transform = targetView.transform.rotated(by: CGFloat(0.0))

    UIView.animate(withDuration: duration, delay: 0.0, options: [.curveLinear, .repeat], animations: {
        targetView.transform = targetView.transform.rotated(by: CGFloat(Double.pi))
    })
}

Upvotes: 3

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