How to press "Back" button in UINavigationController programmatically

I have a UIViewController called FriendsViewController inside a UINavigationController. And a second UIViewController called FriendsDetailedViewController. When navigating from the first view controller to the second, I want to programmatically press the Back button when needed. How to do this?

Simply use

[self.navigationController popViewControllerAnimated:YES]

from FriendsDetailedViewController. Your view will be popped out i.e. the behavior of back button.

Note that it returns UIViewController on normally, and returns nil if there is nothing to pop.

If by pressing "Back" button you mean just to go to the previous view controller, you can just call:

[self.navigationController popViewControllerAnimated:YES];