Black Screen when authetication is completed

I have a strange issue where there is a black screen when my authetication is completed. The data flow (ie authToken) and everything works as expected downstream.

General approach: 

1. Instantiate  GTMOAuth2ViewControllerTouch controller.
2. Config

3. push on top of existing controller

Symptoms:

1. Right before completion handler is called, there is a black border for a split second as shown in the video
2. This does not happen if I were to present the  GTMOAuth2ViewControllerTouch controller instead of pushing it on top of the navigation stack

 
func startGetAuthToken() {
 
 
let oauthViewController : GTMOAuth2ViewControllerTouch = GTMOAuth2ViewControllerTouch.controllerWithScope					(" https://mail.google.com/ 
",
 
 
clientID: CLIENT_ID,
 
 
clientSecret: CLIENT_SECRET,
 
 
keychainItemName: keyChainForAccount,
 
 
completionHandler:
 
 
{ (viewController, retrievedAuth, error) -> Void in
 
 
if let error = error {
 
 
self.userClickedCancel()
 
 
} else {
 
 
self.navigationController?.navigationBarHidden = true
 
 
self.doneFetchingAuth(retrievedAuth)
 
 
}
 
 
}) as! GTMOAuth2ViewControllerTouch
 
 
oauthViewController.authentication.redirectURI = " http://localhost//maildough 
"
 
 
let barButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Cancel,
 
 
target: self,
 
 
action: "userClickedCancel")
 
 
barButtonItem.tintColor = UIColor.whiteColor()
 
 
oauthViewController.navigationItem.setLeftBarButtonItem(barButtonItem, animated: false)
 
 
self.navigationController?.pushViewController(oauthViewController, animated: false)
 
 
//Flag for some downstream operation
 
 
oauthViewControllerShown = true
 
 
}
 
 

 

https://gist.github.com/deltadavid/6fc4a33f669846aa7ab2

Any pointers will be greatly appreciated :D