IOS两种方式制作tabBar底部标签栏目

第一种方式：     //tabBar1添加     NewsViewController *news = [[NewsViewController alloc] init];     UINavViewController *nc1 = [[UINavViewController alloc] initWithRootViewController:news];     nc1.tabBarItem.title = @"栏目1";     nc1.tabBarItem.image = [UIImage imageNamed:@"menu_icon_main.png"];     [nc1.tabBarItem.title sizeWithFont:[UIFont systemFontOfSize:20]];     [news release];     //tabBar2添加     NewsViewController *news2 = [[NewsViewController alloc] init];     UINavViewController *nc2 = [[UINavViewController alloc] initWithRootViewController:news2];     nc2.tabBarItem.title = @"栏目2";     nc2.tabBarItem.image = [UIImage imageNamed:@"menu_icon_main.png"];     [nc2.tabBarItem.title sizeWithFont:[UIFont systemFontOfSize:20]];     [news2 release];  ....NSArray *item = [NSArray arrayWithObjects:nc1,nc2, nil];  //最多可添加5个栏目  UITabBarController *tabBar = [[UITabBarController alloc] init]; [tabBar setDelegate:self];     [tabBar setViewControllers:item];     [self.window setRootViewController:tabBar];     [tabBar release];          [nc1 release];     [nc2 release]第二种方式跟第一种方式稍有所不同     //tabBar1添加     NewsViewController *news = [[NewsViewController alloc] init];     UINavViewController *nc1 = [[UINavViewController alloc] initWithRootViewController:news];     [nc1.tabBarItem.title sizeWithFont:[UIFont systemFontOfSize:20]];     [news release];     //tabBar2添加     NewsViewController *news2 = [[NewsViewController alloc] init];     UINavViewController *nc2 = [[UINavViewController alloc] initWithRootViewController:news2];     nc2.tabBarItem.title = @"栏目2";     nc2.tabBarItem.image = [UIImage imageNamed:@"menu_icon_main.png"];     [nc2.tabBarItem.title sizeWithFont:[UIFont systemFontOfSize:20]];     [news2 release];  ......     NSArray *item = [NSArray arrayWithObjects:nc1,nc2, nil];  //最多可添加5个栏目       UITabBarController *tabBar = [[UITabBarController alloc] init];     UIImageView *tabImgView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"tabbarbg_app.png"]];     [tabImgView setFrame:CGRectMake(0, 436, 320, 44)];         tabBar.tabBar.backgroundImage = [UIImage imageNamed:@"tabbarbg_app.png"];//将栏目名字和栏目标识直接放在一张背景图上     [tabBar setDelegate:self];     [tabBar setViewControllers:item];     [self.window setRootViewController:tabBar];     [tabBar release];          [nc1 release];     [nc2 release];