Issue with adding buttons to UINavigationController - ios

Question

So this is how I make the navbar:
- (void)viewDidLoad
{
[super viewDidLoad];
UINavigationController *navBar = [[UINavigationController alloc] init];
[navBar willMoveToParentViewController:self];
navBar.view.frame = CGRectMake(0, 0, 320, 44);
[self.view addSubview:navBar.view];
[self addChildViewController:navBar];
[navBar didMoveToParentViewController:self];
...
And everywhere I have read says that this is how you add buttons:
UIBarButtonItem *button = [[UIBarButtonItem alloc]initWithTitle:#"test" style:UIBarButtonItemStyleBordered target:self action:#selector(print_message:)];
self.navigationItem.rightBarButtonItem = button;
[button release];
But the button does not show on the navbar. What is wrong with this code?

Answer 1

Unless you're building a custom container view controller (which is a relatively rare thing to do), you should not be building a UINavigationController inside your content controller's -viewDidLoad. While it will provide you a navigation bar, your view controller parent-child relationship will be backwards: your content controller will contain the navigation controller, rather than the other way around.
Instead, you need to create the navigation controller earlier in your app's startup process - maybe in your application delegate, or in your main storyboard if you're using one. Make sure that the new navigation controller has your content controller as its root controller (usually by way of -initWithRootViewController:). Then your self.navigationItem configuration will work properly.

Answer 2

You should create your navigationbar probably differently:
In your xxxAppDelegate.m edit this method:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
// Override point for customization after application launch.
//This is the ViewController of the view you want to be the root
xxxViewController *tvc = [[xxxViewController alloc]init];
//Now you have to initialize a UINavigationController and set its RootViewController
UINavigationController *nvc = [[UINavigationController alloc]initWithRootViewController:tvc];
//Now set the RootViewController to the NavigationViewController
[[self window]setRootViewController:nvc];
self.window.backgroundColor = [UIColor whiteColor];
[self.window makeKeyAndVisible];
return YES;
}
So now you have a proper NavigationController. If you do this in the viewDidLoad method, the NavigationController will be made each time you reload your view.
Now in your xxxViewController.m edit your init method:
- (id)init
{
...
if (self) {
//Create a UINavigationItem
UINavigationItem *n = [self navigationItem];
//Create a new bar button item
UIBarButtonItem *button = [[UIBarButtonItem alloc]initWithTitle:#"test" style:UIBarButtonItemStyleBordered target:self action:#selector(print_message:)];
[[self navigationItem]setRightBarButtonItem:button];
}
return self;
}
This should now display a proper NavigationBar with a UIBarButtonItem.