UIPercentDrivenInteractiveTransition With CABasicAnimation

Question

When using gesture driven UIPercentDrivenInteractiveTransition with CABasicAnimation (or any other CAAnimation), upon finishInteractiveTransition, animation jumps to final position, rather then animating smoothly as is the case when using UIView block animation. I am trying to figure out how to animate smoothly upon finishInteractiveTransition to end when using CAAnimation.

I have now spent whole day on it. There seems to be no mention anywhere about using CAAnimation with custom VC transitions, everyone refers to UIView block based animation.

I have create a small sample project that demonstrates problem.

https://github.com/stringcode86/UIPercentDrivenInteractiveTransitionWithCABasicAnimation

Thank you to anyone who spends time looking at it. I do appreciate it.

Animalcule

Check the repo. Files are missing. Project does not compile. – Chromo

Thank you for taking time looking at it. I fixed the repo, should be all good now – Animalcule

Is there a better fix for this issue available? One without subclassing UIPercentDrivenInteractiveTransition or setting up your own UIViewControllerInteractiveTransitioning. – Roxi

Answer 1

SOLUTION

As it turns out solution is to manipulate layers begin time. I am going to try to explain the solution in bit more depth below. There are two solution one using UIPercentDrivenTransition subclass or implementing UIViewControllerInteractiveTransitioning protocol. Custom UIViewControllerInteractiveTransitioning is on the master branch and UIPercentDrivenTransition implementation is on UIPercentDrivenTransitionImplementation branch.

https://github.com/stringcode86/UIPercentDrivenInteractiveTransitionWithCABasicAnimation

EXPLANATION

UIPercentDrivenTransition uses animations in animateTransition: to implement updateInteractiveTransition: . I am guessing they simply call animateTransition: from startInteractiveTransition: and then set layer (perhaps containers view layer) speed to 0.0 and manipulate its timeOffSet. This allow them to automatically move your transition back and forward. This does it for your UIView animations. Problem with CAAnimations is their begingTime, timeOffSet, speed properties are not set correctly for some reason. If you set those to sensible values, you are able to move all animated content in containerView back and forth. I have created SCPercentDrivenTransition witch is alternative to UIPercentDrivenTransition. You only need to override animateTransition: and call handleGesture: from your gesture recognisers action calls.

Animalcule

what a great explanation. Thank you – Isochromatic

I think you might be the only person in the world who's implemented UIViewControllerInteractiveTransitioning and demonstrated how you can use it outside of the standard percent-driven transition. So bless you! – Grigg