如何以编程方式添加NavigationBarItem和UIBarButtonItem？

Question

I presented a View using a call to presentModalViewController .

My new View didn't have a navigation bar, so I added one from the Library but now when I created a UIBarButtonItem in viewDidLoad of my controller, and set it to rightBarButtonItem of the navigationBarItem .

But when I run my app, the Navigation bar is there but there is no button.

Did I miss a step or something ?

Answer 1

Actually it is easier than this:

1. Drag a UINavigationBar into your app. Note that you will also get a UINavigationItem when you do this... make sure you keep it.

2. Add the following property to your app:

   @property (weak, nonatomic) IBOutlet UINavigationItem *navigationItem;

3. Xcode will likely indicate an error (you are overriding a built in property of UIViewController), so you have to manually synthesize the getter and setter. Add the following line below the @implementation statement for the class:

   @synthesize navigationItem;

4. In Interface Builder, drag a connection from the new navigationItem property to your custom navigation item.

You can now access your navigation item using self.navigationItem, just like you would normally.

Answer 2

Just adding a navigation bar manually will not make the self.navigationController property actual and it's value is nil , which, I believe, you're using for adding a UIBarButtonItem instance.

What I'd recommend is to declare a UINavigationBar IBOutlet in your controller, connect it in NIB editor with navigation bar you've added and after that in viewDidLoad use something like:

@interface ...
@property (nonatomic, retain) IBOutlet UINavigationBar *theBar;
@end

@implementation ...
@synthesize theBar;

-(void)viewDidLoad {
  [super viewDidLoad];

  UIBarButtonItem *yourButton = ...;

  UINavigationItem *item = [[UINavigationItem alloc] initWithTitle:@"MyTitle"];
  item.rightBarButtonItem = yourButton;

  [theBar pushNavigationItem: item animated:NO];
  [item release];

  ...
}

@end

Answer 3

I thought navigationBarItem property of UIViewController is work only if your ViewController is present with UINavigationController

if you add a navigation bar with interface builder or add it with code ,then you need to use - (void)pushNavigationItem:(UINavigationItem *)item animated:(BOOL)animated

to add UINavigationItem yourself

you can create a UINavigationController use - (id)initWithRootViewController:(UIViewController *)yourViewController

and use presentModalViewController to show UINavigationController that you create

then you can use navigationBarItem property of UIViewController to set rightBarButtonItem in viewDidLoad