Open Radar

 
Summary:
When setting an NSFontAttributeName with a custom font to  UISegmentedControl  appearance (some other controls as well)  and then creating a UIDcumentPickerViewController or a UIDocumentMenuController the controller takes up to 7 seconds to show up when presented modally. 
 While using a  UIDocumentMenuController on an iPad  and the user is not logged in on an iCloud account the app will crash with 
- [_UIDimmingKnockoutBackdropView nsli_layoutEngine]%3A message sent to deallocated instance

Steps to Reproduce:
1) Add custom rtf font and set it up on info.plist
2) On AppDelegate set Font appearance for a UISegmentControl
	
    [[UISegmentedControl appearance] setTintColor%3A[UIColor redColor]]%3B
    NSDictionary *attributes %3D %40{
                                 NSFontAttributeName%3A [UIFont fontWithName%3A%40"Pacifico" size%3A16]
                                 }%3B
    
    [[UISegmentedControl appearance] setTitleTextAttributes%3Aattributes forState%3AUIControlStateNormal]%3B

3) Instantiate and present either a UIDcumentPickerViewController or a UIDocumentMenuController

Expected Results:
See the document picker in a reasonable time

Actual Results:
The UI hangs there for up to 7 seconds (the main thread is not frozen and the UI actually responds) and eventually shows the picker.  If the user is not logged in on a iCloud account the app crashes. This is on iPad while trying to present on a popoverPresentationController

Notes:
The file attached is the NewBox example from the Apple website%2C with the modification necessary to reproduce the bug (namely added the fond and the appearance on the app delegate).