Open Radar

 
Summary:
UIViewControllerTransitionCoordinator.h specifies that calling the default implementation of the transitionCoordinator method "will return a transition coordinator if called during an active presentation or dismissal."

However, during an unwind segue between two UIViewControllers on a UINavigationController stack, neither the source or destination view controllers return a transitionCoordinator. Both return nil.

This means it's impossible to specify animations to perform alongside the transition or use the completion block of the transition specify logic to run when the unwind transition is complete.

Steps to Reproduce:
1. Define an unwind segue between two view controllers on a navigation stack
2. In the unwind action method, check the value returned from calling the transitionCoordinator selector on either the source or destination view controllers for the segue.

Expected Results:
A valid transitionCoordinator object is returned for both controllers.

Actual Results:
transitionCoordinator returns nil.

Version:
iOS 7.1