少しカスタマイズする必要があり、それを行うことができます...
// このコードを viewDidLoad に追加します
UIButton *leftButton = [UIButton buttonWithType:UIButtonTypeCustom];
[leftButton setUserInteractionEnabled:NO];
[leftButton setImage:[UIImage imageNamed:@"navigationbutton.png"] forState:UIControlStateNormal];
leftButton.frame = CGRectMake(0, 0, 30, 30);
[leftButton addTarget:self action:@selector(yorrmethod) forControlEvents:UIControlEventTouchUpInside];
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:leftButton];
[leftButton release];
UIButton *rightButton = [UIButton buttonWithType:UIButtonTypeInfoLight];
[rightButton setUserInteractionEnabled : NO];
[rightButton setImage:[UIImage imageNamed:@"navigationbutton.png"] forState:UIControlStateNormal];
rightButton.frame = CGRectMake(0, 0, 30, 30);
[rightButton addTarget:self action:@selector(yourmethod) forControlEvents:UIControlEventTouchUpInside];
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:rightButton];
[rightButton release];
うまくいけば、これはあなたを助けるでしょう...