OC--初始化UINavigationController

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

{

// create a navigation controller and perform some simple styling

self.navigationController = [UINavigationController new];

self.navigationController.navigationBar.barTintColor = [UIColor darkGrayColor];

[self.navigationController.navigationBar setTitleTextAttributes:@{NSForegroundColorAttributeName : [UIColor whiteColor]}];

// create and navigate to a view controller

UIViewController *viewController = [self createInitialViewController];

[self.navigationController pushViewController:viewController animated:NO];

// show the navigation controller

self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

self.window.rootViewController = self.navigationController;

[self.window makeKeyAndVisible];

return YES;

}

- (UIViewController *)createInitialViewController {

self.viewModelServices = [[RWTViewModelServicesImpl alloc] initWithNavigationController:self.navigationController];

self.viewModel = [[RWTFlickrSearchViewModel alloc]

initWithServices:self.viewModelServices];

return [[RWTFlickrSearchViewController alloc]

initWithViewModel:self.viewModel];

}