在AppDelegate（vs viewDidLoad）中选择UI引导代码中的根视图控制器

Question

请原谅我是否问了一些愚蠢的问题（对iOS和swift而言是新的）。我正在尝试在本教程视频的帮助下整合MMDrawerController。

https://www.youtube.com/watch?v=c-Uwa5v_3sc

在本教程中，下面的代码添加到应用程序委托

var window :UIWindow = UIApplication.sharedApplication().keyWindow! 
     let rootViewController = window.rootViewController 
     let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil) 
     let centerViewController = mainStoryboard.instantiateViewControllerWithIdentifier("Category") as! Category 
     let leftViewController = mainStoryboard.instantiateViewControllerWithIdentifier("Menu") as! Menu 

     let leftSideNav = UINavigationController(rootViewController: leftViewController) 
     let centerNav = UINavigationController(rootViewController: centerViewController) 

     centerContainer = MMDrawerController(centerViewController: centerNav, leftDrawerViewController: leftSideNav) 
     centerContainer!.openDrawerGestureModeMask = MMOpenDrawerGestureMode.PanningCenterView; 
     centerContainer!.closeDrawerGestureModeMask = MMCloseDrawerGestureMode.PanningCenterView; 
     window.rootViewController = centerContainer 
     window.makeKeyAndVisible() 

但是当我做，它使应用程序开始centerViewController，但我不认为有什么行为，所以我将该代码移动到centerViewController的viewDidLoad（）上，以为该代码只是连接并启动类，但我认为这出错了。

此外，为了您的信息，我正在通过此代码从集合视图的单元格的tap上调用centerViewController。

var DestViewController = segue.destinationViewController as! UINavigationController 
      let targetController = DestViewController.topViewController as! Category 

现在，只要该代码被称为我的应用程序冻结和应用程序的内存占用不断，直到崩溃增加。

我把日志放在viewDidLoad（）中，发现它是递归调用的。任何人都可以请建议我如何解决这个问题。

谢谢。

更新：

的viewDidLoad功能是这样的

override func viewDidLoad() { 
     super.viewDidLoad() 
     // 
     print("Inside Category") 
     var window :UIWindow = UIApplication.sharedApplication().keyWindow! 
     print("1") 
     let rootViewController = window.rootViewController 
     print("2") 
     let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil) 
     print("3") 
     let centerViewController = mainStoryboard.instantiateViewControllerWithIdentifier("Category") as! Category 
     print("4") 
     let leftViewController = mainStoryboard.instantiateViewControllerWithIdentifier("Menu") as! Menu 

     let leftSideNav = UINavigationController(rootViewController: leftViewController) 
     let centerNav = UINavigationController(rootViewController: centerViewController) 

     centerContainer = MMDrawerController(centerViewController: centerNav, leftDrawerViewController: leftSideNav) 
     centerContainer!.openDrawerGestureModeMask = MMOpenDrawerGestureMode.PanningCenterView; 
     centerContainer!.closeDrawerGestureModeMask = MMCloseDrawerGestureMode.PanningCenterView; 
     window.rootViewController = centerContainer 
     print("5") 
     // window.makeKeyWindow() 
     window.makeKeyAndVisible() 
     print("6") 
     // 
     let tapGestureRecognizerCat = UITapGestureRecognizer(target:self, action:#selector(Category.btnCategoryTapped(_:))) 
     btnCategory.userInteractionEnabled = true 
     btnCategory.addGestureRecognizer(tapGestureRecognizerCat) 
     // 
     let tapGestureRecognizerSearch = UITapGestureRecognizer(target:self, action:#selector(Category.btnSearchTapped(_:))) 
     btnSearch.userInteractionEnabled = true 
     btnSearch.addGestureRecognizer(tapGestureRecognizerSearch) 
     print("7") 
    } 

堆栈跟踪

Inside Category 
1 
2 
3 
4 
5 
6 
7 
Inside Category 
1 
2 
3 
4 
5 
6 
7 
Inside Category 
1 
2 
3 
4 
5 
6 
7 ... and keeps on going like this. 

Answer 1

移动UIWindow/AppDelegate的启动代码viewDidLoad()绝对是 “编码由散弹枪” 的方针，实质上要求View Controller在完成加载后自行重新加载。

在概念级别，您需要了解应用程序生命周期与View Controller生命周期。有这样的体面的苹果开发者文章。我会把搜索留给你。

相反，如果您要覆盖Storyboard的启动机制（请确保您知道您正在进入的内容 - 看起来像是涉足沼泽地，但您没有准备好），然后告诉App Delegate哪个视图控制器是您想要的入口点。您正在查看的是Storyboard（View Controller的属性检查器）中的“is Initial View controller”复选框/右箭头的代码版本。当然，这段代码现在忽略了这个Storyboard设置，所以你需要在代码中进行拼写。

因此，它看起来像：

let viewControllerInstanceThatIReallyWant = mainStoryboard.instantiateViewControllerWithIdentifier("TheStoryBoardIDofTheViewControllerThatIReallyWant") as! ClassOfViewControllerThatIReallyWant 

... 

window.rootViewController = viewControllerInstanceThatIReallyWant 

想必，ClassOfViewControllerThatIReallyWant是一个VC的故事板中的身份，并以某种方式通过你设计任何导航导致相关Category视图控制器。