Open Radar

 
Summary:

- If view controller containment APIs are used to add a child view controller to UIWindow's root view controller in AppDelegate's applicationDidBecomeActive: callback, the viewDidAppear: callback of child view controller is called twice unless child view controller's addition is delayed by at least 0.1 seconds.


Steps to Reproduce:

- Implement applicationDidBecomeActive: in AppDelegate
- Create a new view controller X
- Add X as child view controller of UIWindow's rootViewController


Expected Results:

- viewDidAppear: callback of X is called once


Actual Results:

- viewDidAppear: callback of X is called twice


Regression:

- On iOS 5.0, viewDidAppear: callback is called once also when child view controller's addition is delayed by 0.0 seconds
- On iOS 6.1, viewDidAppear: callback is called twice when child view controller's addition is delayed by 0.0 seconds


Outputs of a test project ("A" is child VC, "Root" is window's root VC):
 ==============
 
 Direct call: [self addChildVC:nil]
 ------------------------------------
 iOS 5.0:
 2013-06-04 17:28:12.095 ChildViewControllerTest[3833:c07] viewWillAppear: Root
 2013-06-04 17:28:12.096 ChildViewControllerTest[3833:c07] addChildVC:
 2013-06-04 17:28:12.097 ChildViewControllerTest[3833:c07] viewWillAppear: A
 2013-06-04 17:28:12.098 ChildViewControllerTest[3833:c07] viewDidAppear: Root
 2013-06-04 17:28:12.099 ChildViewControllerTest[3833:c07] viewDidAppear: A
 2013-06-04 17:28:12.099 ChildViewControllerTest[3833:c07] viewDidAppear: A

 iOS 6.1:
 2013-06-04 17:29:51.691 ChildViewControllerTest[3908:c07] viewWillAppear: Root
 2013-06-04 17:29:51.693 ChildViewControllerTest[3908:c07] addChildVC:
 2013-06-04 17:29:51.694 ChildViewControllerTest[3908:c07] viewWillAppear: A
 2013-06-04 17:29:51.695 ChildViewControllerTest[3908:c07] viewDidAppear: Root
 2013-06-04 17:29:51.695 ChildViewControllerTest[3908:c07] viewDidAppear: A
 2013-06-04 17:29:51.695 ChildViewControllerTest[3908:c07] viewDidAppear: A

 
 With delay == 0.0 sec
 ------------------------------------
 iOS 5.0:
 2013-06-04 17:30:57.187 ChildViewControllerTest[3992:c07] viewWillAppear: Root
 2013-06-04 17:30:57.189 ChildViewControllerTest[3992:c07] viewDidAppear: Root
 2013-06-04 17:30:57.189 ChildViewControllerTest[3992:c07] addChildVC:
 2013-06-04 17:30:57.190 ChildViewControllerTest[3992:c07] viewWillAppear: A
 2013-06-04 17:30:57.190 ChildViewControllerTest[3992:c07] viewDidAppear: A

 iOS 6.1:
 2013-06-04 17:30:37.149 ChildViewControllerTest[3952:c07] viewWillAppear: Root
 2013-06-04 17:30:37.152 ChildViewControllerTest[3952:c07] addChildVC:
 2013-06-04 17:30:37.153 ChildViewControllerTest[3952:c07] viewWillAppear: A
 2013-06-04 17:30:37.153 ChildViewControllerTest[3952:c07] viewDidAppear: Root
 2013-06-04 17:30:37.153 ChildViewControllerTest[3952:c07] viewDidAppear: A
 2013-06-04 17:30:37.154 ChildViewControllerTest[3952:c07] viewDidAppear: A
 
 
 With delay == 0.1 sec
 ------------------------------------
 iOS 5.0:
 2013-06-04 17:32:01.124 ChildViewControllerTest[4080:c07] viewWillAppear: Root
 2013-06-04 17:32:01.126 ChildViewControllerTest[4080:c07] viewDidAppear: Root
 2013-06-04 17:32:01.126 ChildViewControllerTest[4080:c07] addChildVC:
 2013-06-04 17:32:01.127 ChildViewControllerTest[4080:c07] viewWillAppear: A
 2013-06-04 17:32:01.128 ChildViewControllerTest[4080:c07] viewDidAppear: A
 

 iOS 6.1:
 2013-06-04 17:31:26.610 ChildViewControllerTest[4041:c07] viewWillAppear: Root
 2013-06-04 17:31:26.613 ChildViewControllerTest[4041:c07] viewDidAppear: Root
 2013-06-04 17:31:26.713 ChildViewControllerTest[4041:c07] addChildVC:
 2013-06-04 17:31:26.713 ChildViewControllerTest[4041:c07] viewWillAppear: A
 2013-06-04 17:31:26.714 ChildViewControllerTest[4041:c07] viewDidAppear: A