- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];// Override point for customization after application launch.self.window.backgroundColor = [UIColor whiteColor];[self.window makeKeyAndVisible];// MyFirstViewController *viewCtrl1 = [[MyFirstViewController alloc] init]; viewCtrl1.title = @"viewctrl1"; viewCtrl1.view.backgroundColor = [UIColor blueColor]; UINavigationController *navgCtrl1 = [[UINavigationController alloc] initWithRootViewController: viewCtrl1]; // UIViewController *viewCtrl2 = [[UIViewController alloc] init]; viewCtrl2.title = @"viewctrl2"; viewCtrl2.view.backgroundColor = [UIColor redColor]; UINavigationController *navgCtrl2 = [[UINavigationController alloc] initWithRootViewController: viewCtrl2]; // UIViewController *viewCtrl3 = [[UIViewController alloc] init]; viewCtrl3.title = @"viewctrl3"; viewCtrl3.view.backgroundColor = [UIColor yellowColor]; UINavigationController *navgCtrl3 = [[UINavigationController alloc] initWithRootViewController: viewCtrl3]; // UITabBarController *tabBarCtrl = [[UITabBarController alloc] init]; tabBarCtrl.view.frame = self.window.frame; tabBarCtrl.viewControllers = [NSArray arrayWithObjects: navgCtrl1 ,navgCtrl2, navgCtrl3 ,nil]; self.window.rootViewController = tabBarCtrl; return YES; }

- (void)viewDidLoad
{[super viewDidLoad];// Do any additional setup after loading the view.UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];[button addTarget:self action:@selector(Target:) forControlEvents:UIControlEventTouchUpInside];[button setTitle:@"Target" forState:UIControlStateNormal]; button.frame = CGRectMake(100, 200, 120, 44); [self.view addSubview:button]; } -(void)Target:(id)sender { ChangeViewController *changViewCtrl = [[ChangeViewController alloc] init]; [self.navigationController pushViewController:changViewCtrl animated:YES]; }

- (void)viewDidLoad
{[super viewDidLoad];// Do any additional setup after loading the view.self.view.backgroundColor = [UIColor colorWithRed:0.5 green:0.1 blue:0.9 alpha:1.0]; }

UINavigationController *navgCtrl1 = [[UINavigationController alloc] initWithRootViewController: viewCtrl1];

tabBarCtrl.viewControllers = [NSArray arrayWithObjects: navgCtrl1 ,navgCtrl2, navgCtrl3 ,nil];

self.window.rootViewController = tabBarCtrl;