`UIViewControllerTransitionCoordinator` is not properly setup on new instances of `UIViewController` embedded in `UINavigationController`

Originator:elliot
Number:rdar://20171073 Date Originated:16 March 2015
Status:Open Resolved:
Product:iOS SDK Product Version:8.2
Classification:UI and Usability Reproducible:Always
 
# Description

Presenting a `UIViewController` modally as part of a `UINavigationController` when the `UIViewController` is a new instance, `[UIViewController transitionCoordinator]` does not behave as expected.

# Steps to Reproduce

* Create and instance of `UINavigationController`.
* Set a `rootViewController` and present the `UINavigationController` modally.
* Attempt to animate alongside the transition in `[rootViewController viewWillAppear:]` using `[self.transitionCoordinator animateAlongsideTransition:completion:]`.
* The `animation` block of `animateAlongsideTransition:completion:` is never called.

# Expected Results

The `animation` block should be called.

# Actual Results

The `animation` block is not called, but the `completion` block is.

# Configuration

iPhone 6, 64GB, EE (UK), using WiFi

# Version & Build

iOS 8.2 [12D508]

# Additional Notes

When presenting the `UIViewController` directly (i.e. **not** in a `UINavigationController`) the `UIViewControllerTransitionCoordinator` behaves as expected. The sample project attached shows all varieties of presentation and logs to the console when the appropriate blocks are called.

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