UINavigationItem setLeftBarButtonItem animated example in Objective C (iOS).

UINavigationItem setLeftBarButtonItem animated

Sets the custom bar button item, optionally animating the transition to the new item.

- (void)setLeftBarButtonItem:(UIBarButtonItem *)item animated:(BOOL)animated

Parameters of [UINavigationItem setLeftBarButtonItem animated]
item
A custom bar item to display on the left side of the navigation bar.
animated
Specify YES to animate the transition to the custom bar item when this item is the top item. Specify NO to set the item immediately without animating the change.

Discussion of [UINavigationItem setLeftBarButtonItem animated]
If two navigation items have the same custom left or right bar button items, those bar button items remain stationary during the transition when the navigation item is pushed or popped.

UINavigationItem setLeftBarButtonItem animated example.

[super viewDidLoad];
    _navBar = [[UINavigationBar alloc] init];
    [_navBar setFrame:CGRectMake(0,0,self.view.bounds.size.width,52)];
    [self.view addSubview:_navBar];
    UINavigationItem *navItem = [[UINavigationItem alloc]initWithTitle:@""];
    UIBarButtonItem *barButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAction target:self action:@selector(buttonSettingClicked)];
    [navItem setLeftBarButtonItem:barButton animated:NO];

    [_navBar setItems:@[navItem]];

Example of [UINavigationItem setLeftBarButtonItem animated].

UIBarButtonItem *leftBarButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemEdit target:self action:@selector(theEditMethod:)];     
[viewController.navigationItem setLeftBarButtonItem:leftBarButton animated:NO];
[leftBarButton release];

UIBarButtonItem *rightBarButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(theAddMethod:)];      
[viewController.navigationItem setRightBarButtonItem:rightBarButton animated:NO];
[rightBarButton release];

UINavigationItem setLeftBarButtonItem animated example.

Assuming iOS 5 onwards add your custom buttons:

[self.navigationItem setLeftBarButtonItems:[NSArray arrayWithObjects: customBarItem, customBarItemSetting, nil] animated:NO];

End of UINavigationItem setLeftBarButtonItem animated example article.