Fast selective orientation Problems moving from portrait to landscape

Environment:

• Using latest Xcode 8.3
• Language: Swift3
• All devices are up to date (iPhone 7 v10.3.1)
• (Target -> Deployment Information -> Device Orientation) is set to "Portrait" for all "Device" options

Scenario:

• I have 2 ViewControllers (VC1 and VC2), both of which inherit from UIViewController.
• VC1 is always for portrait
• VC2 should always be landscape.
• VC1 and VC2 have all their child objects and objects set up and added to the ViewController in the call to viewDidLoad.

• I am representing VC2 from VC1 via a call (since I need a navigation bar):

  let vc2 = UINavigationController(rootViewController: VC2())
  self.present(vc2, animated: true, completion: nil)
  
        
  
          
          
          
        
  
      

• Whether VC2 inherits from UINavigationController or UIViewController has nothing to do with the problem.

• AppDelegate.swift provides orientation as such:

  func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {
      if let rootViewController = self.topViewControllerWithRootViewController(rootViewController: window?.rootViewController) {
          if rootViewController is VC2 {
          let vc2 = rootViewController as! VC2
          if vc2.isPresented {
              return .landscapeRight
          }
      }
      return .portrait
  }
  
        
  
          
          
          
        
  
      

• The above function uses this function to find the topViewControllerWithRootViewController:

  private func topViewControllerWithRootViewController(rootViewController: UIViewController!) -> UIViewController? {
      if (rootViewController == nil) {
          return nil
      }
      if (rootViewController.isKind(of: UITabBarController.self)) {
          return topViewControllerWithRootViewController(rootViewController: (rootViewController as! UITabBarController).selectedViewController)
      } else if (rootViewController.isKind(of: UINavigationController.self)) {
          return topViewControllerWithRootViewController(rootViewController: (rootViewController as! UINavigationController).visibleViewController)
      } else if (rootViewController.presentedViewController != nil) {
          return topViewControllerWithRootViewController(rootViewController: rootViewController.presentedViewController)
      }
      return rootViewController
  }
  
        
  
          
          
          
        
  
      

Question:

• This usually always works, however in some cases the view will cause the VC2 to be presented vertically, properties are obtained from the horizontal view:

Here

• This happens randomly, with no errors showing up in Xcode (including the debug console).

Additional Notes:

• Note that the background thread is running tasks that require the use of the GPU. They are declared from ViewControllers other than VC1 and VC2.
• It is possible that this could cause the time-sensitive orientation functions of the device to be called in the wrong order.
• I have tried implementations from the following links:

http://www.jairobjunior.com/blog/2016/03/05/how-to-rotate-only-one-view-controller-to-landscape-in-ios-slash-swift/