Setting UIViewController preferredContentSize not working in iOS 17

Question

In iOS 17, I am having an issue where UIPopoverPresentationControllers are not retaining the preferred size of the UIViewController they contain.

The following method uses a UIPopoverPresentationController popoverVC to display a UIViewController contentVC from a UIView view anchor location frame.

+ (void) showDialogiPad:(UIViewController *)contentVC
       fromPresentingVC:(UIViewController *)presentingVC
                 inView:(UIView *)view
                atFrame:(CGRect)frame
          withDirection:(UIPopoverArrowDirection)direction {
    
    // Set content view controller size
    contentVC.preferredContentSize = contentVC.view.frame.size; // size should be 320x480
        
    // Choose the presentation style in which the content is
    // displayed in a popover view
    contentVC.modalPresentationStyle = UIModalPresentationPopover;
    
    // Set the popover size and anchor location
    contentVC.popoverPresentationController.sourceRect = frame;
    contentVC.popoverPresentationController.sourceView = view;
    
    // Present the popover presentation controller
    [presentingVC presentViewController:contentVC animated:YES completion:nil];
}

The contentVC's size gets set in it's viewDidLoad method as follows:

- (void)viewDidLoad {
    
    [super viewDidLoad];

    // Set the size of this view controller (which is used in a popup view controller)
    self.view.frame = CGRectMake(0, 0, 320, 480);
    
    // Set a border around the view
    CALayer *layer = self.view.layer;
    layer.borderColor = [[UIColor darkGrayColor] CGColor];
    layer.borderWidth = 2;
    layer.cornerRadius = 10;
}

Prior to iOS 17, the code displayed the popover as expected as shown here:

Now however, since the update to iOS 17, the popover is now squashed and displayed as:

A few observations:

• The popover dialog actually displays properly the first time you open it. Every subsequent time you open it, it is squashed.
• When I comment out the line that sets the preferredContentSize, the popover opens at the max size every time - so it shows all the content but it is not set to the size I want it to be.
• If I leave preferredContentSize as is but change modalPresentationStyle to UIModalPresentationFormSheet, the size of the popover is correct but the popover always presents in the middle of the screen.

Answer 1

I find that in many cases, instead of externally setting a view controller's preferredContentSize property to some value, it works better if the given view controller overrides the preferredContentSize property. This also has the benefit of putting the knowledge of the preferred size in the view controller itself.

- (CGSize)preferredContentSize {
    return CGSizeMake(width: 320, height: 480);
}