How do I change the title of the "back" button on a Navigation Bar

Here is the documentation for backBarButtonItem:

"When this navigation item is immediately below the top item in the stack, the navigation controller derives the back button for the navigation bar from this navigation item. [...] If you want to specify a custom image or title for the back button, you can assign a custom bar button item (with your custom title or image) to this property instead."

View Controller A (the "parent" view controller):

self.title = @"Really Long Title";
UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:@"Short" style:UIBarButtonItemStyleBordered target:nil action:nil];
self.navigationItem.backBarButtonItem = backButton;

When any other view controller B is on top of the navigation stack, and A is right below it, B's back button will have the title "Short".

This should be placed in the method that calls the ViewController titled "NewTitle". Right before the push or popViewController statement.

UIBarButtonItem *newBackButton = 
        [[UIBarButtonItem alloc] initWithTitle:@"NewTitle" 
                                         style:UIBarButtonItemStyleBordered 
                                        target:nil 
                                        action:nil];
[[self navigationItem] setBackBarButtonItem:newBackButton];
[newBackButton release];

In ChildVC this worked for me...

self.navigationController.navigationBar.topItem.title = @"Back";

Works in Swift too!

self.navigationController!.navigationBar.topItem!.title = "Back"

in Xcode 4.5 using storyboard, by far the easiest solution i've found when the value of the Back button doesn't have to change dynamically is to use the "Back Button" field associated with the Navigation Item of the View Controller to which you want the "Back" button to say something else.

e.g. in the screenshot below, i want the Back button for the view controller(s) that i push to have "Back" as the title of the Back button.

of course, this won't work if you need the back button to say something slightly different each time … there are all of the other solutions here for that.