iOS開發手記 - iOS9.3 UINavigationController添加后不顯示storyboard中viewcontroller里的控件的解決方法

我原先是這么做的，通常也是這么做

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    ViewController *firstVC = [[ViewController alloc] init];
    UINavigationController *naviController = [[UINavigationController alloc] initWithRootViewController:firstVC];
    self.window.rootViewController = naviController;
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    return YES;
}
 

 然而運行后，UINavigationController的確作為windows的根視圖顯示了，但是firstVC里的控件卻沒有顯示，一片空白

事實證明不能這樣直接alloc firstVC，而是要從storyboard中加載，我改成如下就行了：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    UIStoryboard *storyBoard = [UIStoryboard storyboardWithName:@"Main_" bundle:nil];
    ViewController *firstVC = [storyBoard instantiateViewControllerWithIdentifier:@"MainView"];
    UINavigationController *naviController = [[UINavigationController alloc] initWithRootViewController:firstVC];
    self.window.rootViewController = naviController;
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    return YES;
}

我查看過很多代碼例子都是像前者一樣直接alloc加載就可以，但是我這里卻不行，一定要這樣從storyboard中加載，我哪里沒注意到望大神告知