iOS開發手記 - iOS9.3 UINavigationController添加後不顯示storyboard中viewcontroller裏的控件的解決方法

我原先是這麼作的，一般也是這麼作

- (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;
}
 

 然而運行後，UINavigationController的確做爲windows的根視圖顯示了，可是firstVC裏的控件卻沒有顯示，一片空白

事實證實不能這樣直接alloc firstVC，而是要從storyboard中加載，我改爲以下就好了：

- (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;
}

我查看過不少代碼例子都是像前者同樣直接alloc加載就能夠，可是我這裏卻不行，必定要這樣從storyboard中加載，我哪裏沒注意到望大神告知