Question

I want to show the UIBarButtonItem and UINavigationItem through code in the method viewWillAppear

Answer 1

You’ll need to give a little more details, but probably you mean something like this:

UIBarButtonItem *btn = [[UIBarButtonItem alloc] initWithTitle: @"Back" 
                                         style: UIBarButtonItemStylePlain 
                                        target: self 
                                        action: @selector(backAction)];
self.navigationItem.leftBarButtonItem = btn;
[btn release];