How do I hide/show the right button in the Navigation Bar

Question

I need to hide the right button in the Navigation Bar, then unhide it after the user selects some options.

Unfortunately, the following doesn\'t work:

Answer 1

Show:

[self.navigationItem.rightBarButtonItem.customView setAlpha:1.0];

Hide:

[self.navigationItem.rightBarButtonItem.customView setAlpha:0.0];

You can even animate its showing/hiding

[UIView animateWithDuration:0.2 animations:^{
        [self.navigationItem.rightBarButtonItem.customView setAlpha:1.0];

    }];