UIKit crash in + [UIViewAnimationState popAnimationState]

Question

UIKit crash in + [UIViewAnimationState popAnimationState]

According to Crashlytics, I have a very frequent crash in my application in +[UIViewAnimationState popAnimationState]

This only happens on iOS 10, but applies to iPhone and iPad.

EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x0000000000000008
Crashed: com.apple.main-thread
0  UIKit                          0x230d57ce +[UIViewAnimationState popAnimationState] + 93
1  UIKit                          0x2336c79d -[UIViewAnimationState _runConstraintBasedLayoutAnimations] + 740
2  UIKit                          0x230d4755 +[UIView(UIViewAnimationWithBlocks) _setupAnimationWithDuration:delay:view:options:factory:animations:start:animationStateGenerator:completion:] + 584
3  UIKit                          0x232f8a4b +[UIView(UIViewAnimationWithBlocks) animateWithDuration:delay:usingSpringWithDamping:initialSpringVelocity:options:animations:completion:] + 168
4  UIKit                          0x239b0329 -[UIAlertControllerVisualStyleAlert animateAlertControllerView:ofAlertController:forPresentation:inContainerView:descendantOfContainerView:duration:completionBlock:] + 536
5  UIKit                          0x23682773 -[_UIAlertControllerAnimatedTransitioning _animateTransition:completionBlock:] + 808
6  UIKit                          0x23682057 -[_UIAlertControllerAnimatedTransitioning animateTransition:] + 534
7  UIKit                          0x233d8c43 __56-[UIPresentationController runTransitionForCurrentState]_block_invoke + 3346
8  UIKit                          0x2331e983 _runAfterCACommitDeferredBlocks + 276
9  UIKit                          0x23311c93 _cleanUpAfterCAFlushAndRunDeferredBlocks + 524
10 UIKit                          0x230938bd _afterCACommitHandler + 112
11 CoreFoundation                 0x1de2f803 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 20
12 CoreFoundation                 0x1de2da55 __CFRunLoopDoObservers + 282
13 CoreFoundation                 0x1de2e017 __CFRunLoopRun + 1358
14 CoreFoundation                 0x1dd811af CFRunLoopRunSpecific + 470
15 CoreFoundation                 0x1dd80fd1 CFRunLoopRunInMode + 104
16 GraphicsServices               0x1f52bb41 GSEventRunModal + 80
17 UIKit                          0x23103a53 UIApplicationMain + 150
18 My App                         0x10dbaf main (main.m:14)
19 libdyld.dylib                  0x1d56e4eb start + 2

At first, I had no idea what caused this crash, but after a few months I had enough user reports that I managed to narrow down to this Swift code:

// Show a popup to ask for the new category name
let alert : UIAlertController = UIAlertController(title: "Alert", message: "Message", preferredStyle: UIAlertControllerStyle.alert);

alert.addTextField(configurationHandler: { (textField : UITextField) in

});

alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: { (action : UIAlertAction) in
        // Do something here
}));
alert.addAction(UIAlertAction(title: "Cancel", style: UIAlertActionStyle.cancel, handler:nil));

myViewController.present(alert, animated: true, completion: nil);