Open Radar

 
On iPad, when using `preferredContentSize` on UIImagePickerController presented as `.formSheet`, when selecting from the library and navigating to the gallery view after selecting an album, if a layout is triggered, such as a device rotation, the view is resized to compact size instead of maintaining the requested size.

Steps to Reproduce:

1. Use the following to present a UIImagePickerController on an iPad:

class ViewController: UIViewController, UINavigationControllerDelegate {

    static private let preferredContentSize = CGSize(width: 540, height: 710)
  
    private func showPhotoLibrary() {
        let imagePicker = UIImagePickerController()
        imagePicker.modalPresentationStyle = .formSheet
        imagePicker.delegate = self
        imagePicker.sourceType = .photoLibrary
        imagePicker.preferredContentSize = ViewController.preferredContentSize

        present(imagePicker, animated: true, completion: nil)
    }

2. Select an album, you should now be viewing the collection view of images
3. Rotate the iPad

Expected Results:

Picker maintains width

Actual Results:

Picker resizes to Compact width.

Version/Build:

iOS 11.2.5 and 11.3 beta 5

Configuration:

iPad Pro 9.7

Workaround:

You can workaround the problem by implementing the nav controller willShow delegate method thusly:

    public func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {
        viewController.preferredContentSize = ViewController.preferredContentSize
    }