Setting Toolbar Items of UINavigationController

问题:

In iPhone OS 3.0, you can set the toolbar items of a UINavigationController using the setToolbarItems:animated: method. However, this requires you pass in an array of UIToolbarItems. While I could programmatically create these toolbar items, I'd rather create them in Interface Builder if possible.

With this in mind, I have created a UIToolbar in "MyGreatViewController.xib" and have populated it with the wanted toolbar items. Then, in "MyGreatViewController.m", I get the items from the toolbar and pass them to setToolbarItems:animated::

- (void)viewDidLoad {
    [super viewDidLoad];
    [self setToolbarItems: [toolbar items]];
}

...where toolbar is an IBOutlet referring to the UIToolbar.

Is this a good approach? Is there a better way to accomplish this? Should I just create the items programmatically?

回答1:

It's a perfectly acceptable way of doing it, but do bear in mind that loading xib files is quite expensive on the iPhone, and it may well be faster to create the toolbar items programatically in your viewDidLoad method.

回答2:

I don't know if this is documented anywhere, but I've found that in Interface Builder, if you enable the navigation controller's toolbar, you can drag bar items to your view controller, and they will automagically show up in the navigation controller's toolbar.

For example, here's what we can do (using Xcode 3.2 on Snow Leopard):

1. File->New Project.... Choose Navigation-based Application and create the project.
2. Open MainWindow.xib in Interface Builder.
3. Select the Navigation Controller, and in the Attributes inspector, check the "Shows Toolbar" box. This will cause a Toolbar object to appear.
4. Drag a Bar Button Item from the Library to the toolbar. It will appear in the toolbar. If you check the hierarchy in the NIB, you'll see that this new item is a child of the RootViewController.

It seems that any Bar Button Items added as children of the navigation item will show up in the navigation bar, and any Bar Button Items added as children of the view controller will show up in the toolbar.

(I stumbled on this by accident. If anyone can find documentation for this behavior, or any additional info, I'd like to hear about it.)