ios – 当没有后退按钮时,将左侧的条形按钮项添加到UINavigationController

我想在我的导航栏中添加一个默认的左栏按钮项.只有当UINavigationController没有提供后退按钮时才应该显示.

什么是最好的方法？

解决方法

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
    if(navigationController.viewControllers.count != 1) { // not the root controller - show back button instead
        return;
    }
    UIBarButtonItem *menuItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemOrganize
                                                                              target:self
                                                                              action:@selector(menuItemSelected:)];   
    [viewController.navigationItem setLeftBarButtonItem:menuItem]; 
}