Please note, this blog entry is from a previous course. You might want to check out the current one.
The seventh lecture addresses the interaction of multiple model-view controllers – especially navigation controllers.
The links between two view controllers are called segues. They always create a new instance of the called MVC and need to initialize that MVC e.g. using prepareForSegue.
Segues can also be prevented from happening using shouldPerformSegueWithIdentifier.
Where tab-bar, split-view and navigation controllers are view controllers, popovers are not. Though preparing popover segues works similar, their destruction needs special care, making the calling view controller the delegate.