How to hide the "back" button in UINavigationController?

Question

I just found out the answer, in a controller use this:

[self.navigationItem setHidesBackButton:YES animated:YES];

And to restore it:

[self.navigationItem setHidesBackButton:NO animated:YES];

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[UPDATE]

Swift 3.0:

self.navigationItem.setHidesBackButton(true, animated:true)

Add this Code

[self.navigationItem setHidesBackButton:YES];

In addition to removing the back button (using the methods already recommended), don't forget the user can still 'pop' to the previous screen with a left-to-right swipe gesture in iOS 7 and later.

To disable that (when appropriate), implement the following (in viewDidLoad for example):

 if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0)
     self.navigationController.interactivePopGestureRecognizer.enabled = NO;

Just to clarify existing answers: the hidesBackButton property is the right answer, but it isn't clear in many answers what self refers to. Basically you should set self.navigationItem.hidesBackButton = YES in the view controller that is about to get pushed (or just got pushed) onto the UINavigationController.

In other words, say I have a UINavigationController named myNavController. I want to put a new view on it, and when I do I don't want the back button to show anymore. I could do something like:

UIViewController *newVC = [[UIViewController alloc] init];
//presumably would do some stuff here to set up the new view controller
newVC.navigationItem.hidesBackButton = YES;
[myNavController pushViewController:newVC animated:YES];

When the code finishes, the view controlled by newVC should now be showing, and no back button should be visible.