iOS开发手记 - iOS9.3 UINavigationController添加后不显示storyboard中viewcontroller里的控件的解决方法

我原先是这么做的，通常也是这么做

- (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;
}

然而运行后，UINavigationController的确作为windows的根视图显示了，但是firstVC里的控件却没有显示，一片空白

事实证明不能这样直接alloc firstVC，而是要从storyboard中加载，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;
}

我查看过很多代码例子都是像前者一样直接alloc加载就可以，但是我这里却不行，一定要这样从storyboard中加载，我哪里没注意到望大神告知