When dismissing a view controller on top of a view controller with UIModalPresentationPageSheet or UIModalPresentationFormSheet, the presenting view controllers frame and transform can get miscomputed on iOS 7. Here is a fix I used in SPLSpeechBubblePopoverController:
@implementation UIViewController (SPLSpeechBubblePopoverControllerHack)
+ (void)load
{
class_swizzleSelector(self, @selector(dismissViewControllerAnimated:completion:), @selector(__SPLSpeechBubblePopoverControllerDismissViewControllerAnimated:completion:));
}