显示UIAlertViewController时，XCODE iphone 6 plus和6s plus会显示警告

Question

I'm a newbie in iOS development. I was trying to display a UIAlertController when a button is clicked (The storyboard is empty, there's only 1 button in the storyboard), using below code

@IBAction func showAlert(sender: UIBarButtonItem) {
  let alert = UIAlertController(
    title: "Create new",
    message: "Hi",
    preferredStyle: UIAlertControllerStyle.Alert
  )

  let createAction = UIAlertAction(title: "Ok", style: .Default, handler: nil)
  let cancelAction = UIAlertAction(title: "Cancel", style: .Cancel, handler: nil)

  alert.addAction(createAction)
  alert.addAction(cancelAction)
  alert.addTextFieldWithConfigurationHandler {
    $0.placeholder = "Test placeholder"
  }

  presentViewController(alert, animated: true, completion: nil)
}

iphone 5, 5s, 6, 6s do not show warnings, however iphone 6plus and 6s plus shows warning

2015-10-20 22:38:54.007 TestApp[3128:48601] the behavior of the UICollectionViewFlowLayout is not defined because: 2015-10-20 22:38:54.008 TestApp[3128:48601] the item height must be less than the height of the UICollectionView minus the section insets top and bottom values, minus the content insets top and bottom values. 2015-10-20 22:38:54.008 TestApp[3128:48601] The relevant UICollectionViewFlowLayout instance is <_UIAlertControllerCollectionViewFlowLayout: 0x7fd6b8582d90>, and it is attached to ; layer = ; contentOffset: {0, 0}; contentSize: {0, 0}> collection view layout: <_UIAlertControllerCollectionViewFlowLayout: 0x7fd6b8582d90>.

If I remove the text field on UIAlertController or I remove the 2 buttons (keep the text field displayed), it does not show warnings. Any explanation why this happens? How to fix the warning?

Answer 1

try:

yourAlertController.view.setNeedsLayout()

just before presenting it with presentViewController:

edit: I have submitted this bug to Apple

Answer 2

I also had same issue in my screen for only iphon6 plus screen. Please check, if you are not passing empty title, if title is empty , pass it nil like :

UIAlertController *confirmAlert = [UIAlertController alertControllerWithTitle:nil message:displayMessage preferredStyle:UIAlertControllerStyleAlert];

instead of

  UIAlertController *confirmAlert = [UIAlertController alertControllerWithTitle:@"" message:displayMessage preferredStyle:UIAlertControllerStyleAlert];

it fixed my problem. Good luck..