【iOS】設置 rootViewController

iOS 開發中，rootViewController 經常用到，示例代碼如下：

self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
self.window.backgroundColor = [UIColor whiteColor];
    
// 設置相應的 ViewController
ViewController *vc = [[ViewController alloc] init];
self.window.rootViewController = vc;

[self.window makeKeyAndVisible];