iPhone SDK開發基礎之
使用UITabBarController組織和管理UIView
當你的程式分為幾個相對比較獨立的部分時，就比較适合使用UITabBarController來組織使用者界面，如圖3-26所示。
在螢幕的下方包含UITabBarController的三個按鈕，使用者單擊不同的按鈕即可以進入不同的界面，每個界面相對來說在整個系統中比較獨立，也就是程式分成了三個相對比較獨立的不同部分，在每個相對獨立的部分你也可以使用UINavigationController等容器類組織你的界面。這樣組織使程式邏輯非常清晰，當然你也可以組織很多個Tab而不隻是三個，以下代碼示範如何建立UITabBarController對象，并為其添加多個Tab。
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions: (NSDictionary *)launchOptions {
// Override point for customization after application launch.
//Create the navigation Controller
UINavigationController *localNavigationController;
//Create UINavigationController
tabBarController = [[UITabBarController alloc] init];
tabBarController.delegate = self;
// Create the array that will contain all the View controlelr
NSMutableArray *localControllersArray = [[NSMutableArray alloc] init WithCapacity:3];
// Create the view controller attached to the first item in the TabBar
aViewController *firstViewController;
firstViewController = [aViewController alloc];
localNavigationController = [[UINavigationController alloc] initWithRoot ViewController:firstViewController];
localNavigationController.navigationBar.barStyle = UIBarStyleBlackOpaque;
[localNavigationController.tabBarItem initWithTitle:@"Outlines"
image:[UIImage imageNamed:@"webcast.png"] tag:1];
firstViewController.navigationItem.title = @"Outlines";
[localControllersArray addObject:localNavigationController];
[localNavigationController release];
[firstViewController release];
// Create the view controller attached to the second item in the TabBar
anotherViewController *secondViewController;
secondViewController = [[anotherViewController alloc] initWithStyle: UITableViewStyleGrouped ];
localNavigationController = [[UINavigationController alloc] initWithRoot ViewController:secondViewController];
[localNavigationController.tabBarItem initWithTitle:@"Q & A"
image:[UIImage imageNamed:@"book.png"] tag:2];
[email protected]"Q & A";
[localControllersArray addObject:localNavigationController];
[localNavigationController release];
[secondViewController release];
miscViewController *thirdViewController;
thirdViewController = [[miscViewController alloc] initWithStyle:UITable ViewStyleGrouped ];
localNavigationController = [[UINavigationController alloc] initWithRoot ViewController:thirdViewController];
[localNavigationController.tabBarItem initWithTitle:@"Misc"
image:[UIImage imageNamed:@"favorites.png"] tag:3];
[email protected]"Misc";
[localControllersArray addObject:localNavigationController];
[localNavigationController release];
[thirdViewController release];
// load up our tab bar controller with the view controllers
tabBarController.viewControllers = localControllersArray;
// release the array because the tab bar controller now has it
[localControllersArray release];
// add the tabBarController as a subview in the window
[window addSubview:tabBarController.view];
// need this last line to display the window (and tab bar controller)
[window makeKeyAndVisible];
return YES;
}
捕獲Tab切換事件，擷取目前活動的Tab索引和UIViewController對象，代碼如下。
- (void)tabBarController:(UITabBarController *)barController didSelectView Controller:(UIViewController *)viewController{
NSLog(@"currentController index:%d"，viewController， tabBarController.selectedIndex);
UIViewController *currentController = tabBarController.selectedView Controller;
NSLog(@"currentController: %@"，currentController);
}
切換不同的Tab時，隻需要設定UITabBarController的selectedIndex屬性即可，代碼如下。
tabBarController.selectedIndex = 2;
本節相關的完整Xcode工程源代碼檔案請參考本書附帶的CD光牒中的Lessons2執行個體。
本文節選自《iOS軟體開發揭密：iPhone&iPad企業應用和遊戲開發》一書。
《iOS軟體開發揭密：iPhone&iPad企業應用和遊戲開發》一書已由電子工業出版社正式出版，本書由虞斌著。
互動出版網:http://product.china-pub.com/198191