In WWDC 2011 Session 102, Apple introduced View Controller Containment, which is the ability to create custom view controller containers, analogous to UITabBarController, UINavigationController, and the like.
I watched the examples several times. There are a flurry of methods associated with this pattern, but it was a little hard to figure them out exactly. I'm going to post here what I think is going on and see if the community will confirm or disconfirm my suspicions.
Scenario 1: Moving from no parent to a new parent view controller
[vc willMoveToParentViewController:self];
[self addChildViewController:vc];
[self.view addSubview:vc.view]; // or something like this.
[vc didMoveToParentViewController:self];
Do the first two lines have to occur in the order given, or can they be reversed?
Scenario 2: Moving from a parent view controller to no parent view controller
[vc willMoveToParentViewController:nil];
[vc.view removeFromSuperview];
[vc removeFromParentViewController];
Is it also necessary to call [vc didMoveToParentViewController:nil]? The examples in Session 102 did not do this in this scenario, but I don't know whether that was an omission or not.
Scenario 3: Moving from one parent view controller to another
This will likely occur in the following way, because the logic in each parent view controller will be encapsulated.
// In the old parent
[vc willMoveToParentViewController:nil];
[vc.view removeFromSuperview];
[vc removeFromParentViewController];
// In the new parent
[vc willMoveToParentViewController:self];
[self addChildViewController:vc];
[self.view addSubview:vc.view];
[vc didMoveToParentViewController:self];
Questions
My main question is this: Is this how view controller containment shoul