iOS 16 -viewWillTransitionToSize:withTransitionCoordinator: bizarre value in the size parameter ((CGSize) size = (width = 414, height = 394)) on iPhone 14 Pro Max?

Question

Created Sep ’22

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I noticed a bug on rotation change in my app on iPhone 14 Pro Max simulator. Basically a view in my view hierarchy is hidden when it shouldn't be. In landscape mode there isn't enough room for this view so I hide it on the iPhone (not essential). But when tilting back to portrait mode I unhide it.

-(void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator

{
    [super viewWillTransitionToSize:size withTransitionCoordinator:coordinator];
    BOOL isIPhone = UIDevice.currentDevice.userInterfaceIdiom == UIUserInterfaceIdiomPhone;
   BOOL isIPhoneAndGoingLandscapeMode = (isIPhone
                                          && size.width > size.height);

   if (isIPhoneAndGoingLandscapeMode) 
  {
       self.someView.hidden = YES;
  }
  else
  {
       self.someView.hidden = NO;
  }
}

So this view controller is presented modally (form sheet style).

On iPhone 14 Pro Max on orientation -viewWillTransitionToSize:withTransitionCoordinator: is called twice and the size parameter is always:

(CGSize) size = (width = 414, height = 394)

This is the sized passed to my app when rotating to portrait and landscape so my isIPhoneAndGoingLandscapeMode flag always is YES because 414 > 394. The 414 x 394 size appears to be false.

My view controller's view in landscape on iPhone 14 pro max logs out to:

(origin = (x = 0, y = 0), size = (width = 932, height = 430))

And 932 x 430 is the size I expected to be passed to me in -viewWillTransitionToSize:withTransitionCoordinator:

Unless I'm missing something can this behavior be explained?

Boost

Answer 1

Macho Man Randy Savage OP

Sep ’22

I opened FB11580679

0

Answer 2

Macho Man Randy Savage OP

Sep ’22

Potential workaround:

 [coordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext>  _Nonnull context)

    {
        UIView *container = context.containerView;
        CGRect containerFrame = container.frame;
        CGSize authenticSize = containerFrame.size; //use the size from the container view to workaround bogus size.

    }

    completion:nil];

Also tried moving this code to -traitCollectionDidChange: but it looks better if the view gets hidden before the rotation, not after.

0

Answer 3

Macho Man Randy Savage OP

Sep ’22

Heh this weird size is also passed to iPhone 13 Pro Max (even on IOS 15) but I didn't notice before because I also update the hidden property in -viewDidLayoutSubviews if landscape/iPhone combination is detected and on iOS 15 -viewDidLayoutSubviews is called after -viewWillTransitionToSize:withTransitionCoordinator:

What makes this an issue in my app on iOS 16 is UIKit is now making an extra call to -viewWillTransitionToSize:withTransitionCoordinator: after viewDidLayoutSubviews (with the bogus size), so the call to hide the view in -viewWillTransitionToSize:withTransitionCoordinator: ends up winning.

Another potential workaround is to move this code out of -viewWIllTransitionToSize:withTransitionCoordinator and into -viewWillLayoutSubviews OR use -willTransitionToTraitCollection:withTransitionCoordinator:

-(void)willTransitionToTraitCollection:(UITraitCollection*)newCollection withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator
{
//iPhone going landscape...translate the size class abstraction into normal terms.
    if (newCollection.userInterfaceIdiom == UIUserInterfaceIdiomPhone
        && newCollection.verticalSizeClass == UIUserInterfaceSizeClassCompact)
    {
         //do it.
    }
    [super willTransitionToTraitCollection:newCollection
                 withTransitionCoordinator:coordinator];
}

Looks like iOS may have stopped passing in the final destination size to -viewWillTransitionToSize:withTransitionCoordinator: in iOS 15, for unknown reasons. This is all from within a view controller presented modally.

0