UITabBarItem Class Reference

Inherits from	UIBarItem : NSObject
Conforms to	NSObject (NSObject)
Framework	/System/Library/Frameworks/UIKit.framework
Availability	Available in iOS 2.0 and later.
Declared in	UITabBarItem.h

Overview

The UITabBarItem class implements an item on a tab bar, instances of the UITabBar class. A tab bar operates strictly in radio mode, where one item is selected at a time‚Äîtapping a tab bar item toggles the view above the tab bar. You can also specify a badge value on the tab bar item for adding additional visual information‚Äîfor example, the Phone application uses a badge on the item to show the number of new messages. This class also provides a number of system defaults for creating items.

Use the initWithTabBarSystemItem:tag: method to create one of the system items. Use the initWithTitle:image:tag: method to create a custom item with the specified title and image.

Tasks

Initializing a Item

Getting and Setting Properties

Properties

For more about Objective-C properties, see “Properties” in The Objective-C Programming Language.

badgeValue

Text that is displayed in the upper-right corner of the item with a surrounding red oval.

@property(nonatomic, copy) NSString *badgeValue

Discussion

The default value is nil.

Availability

Available in iOS 2.0 and later.

Declared In

UITabBarItem.h

Instance Methods

initWithTabBarSystemItem:tag:

Creates and returns a new item containing the specified system item.

- (id)initWithTabBarSystemItem:(UITabBarSystemItem)systemItem tag:(NSInteger)tag

Parameters

systemItem: The system item to use as the first item on the tab bar. One of the constants defined in UITabBarSystemItem.
tag: The receiver‚Äôs tag, an integer that you can use to identify bar item objects in your application.

Return Value

A newly initialized item containing the specified system item. The item‚Äôs target is nil.

Discussion

This method returns a system-supplied tab bar item. The title and image properties of the returned item cannot be changed later.

Availability

Available in iOS 2.0 and later.

Declared In

UITabBarItem.h

initWithTitle:image:tag:

Creates and returns a new item using the specified properties.

- (id)initWithTitle:(NSString *)title image:(UIImage *)image tag:(NSInteger)tag

Parameters

title

The item‚Äôs title. If nil, a title is not displayed.

image

The item‚Äôs image. If nil, an image is not displayed.

The images displayed on the tab bar are derived from this image. If this image is too large to fit on the tab bar, it is scaled to fit. The size of an tab bar image is typically 30 x 30 points. The alpha values in the source image are used to create the unselected and selected images‚Äîopaque values are ignored.

tag

The receiver‚Äôs tag, an integer that you can use to identify bar item objects in your application.

Return Value

Newly initialized item with the specified properties.

Availability

Available in iOS 2.0 and later.

Declared In

UITabBarItem.h

Constants

UITabBarSystemItem

System items that can be used on a tab bar.

typedef enum {
   UITabBarSystemItemMore,
   UITabBarSystemItemFavorites,
   UITabBarSystemItemFeatured,
   UITabBarSystemItemTopRated,
   UITabBarSystemItemRecents,
   UITabBarSystemItemContacts,
   UITabBarSystemItemHistory,
   UITabBarSystemItemBookmarks,
   UITabBarSystemItemSearch,
   UITabBarSystemItemDownloads,
   UITabBarSystemItemMostRecent,
   UITabBarSystemItemMostViewed,
} UITabBarSystemItem;