swift - 将 View 添加到窗口层次结构

Question

我正在尝试在我的游戏中创建一个暂停屏幕。我在 Storyboard中添加了一个“PauseScreen”viewController， Storyboard ID 和恢复 ID 设置为“PauseScreenID”，并移动到暂停屏幕，我在“GameScene”中创建了该功能:

func pauseSceenTransition(){

    let viewController = UIStoryboard(name: "Main", bundle:nil).instantiateViewControllerWithIdentifier("PauseScreenID") as UIViewController

    let currentViewController = (UIApplication.sharedApplication().delegate as AppDelegate)

    currentViewController.window?.rootViewController?.presentViewController(viewController, animated: false, completion: nil)
}

但是当它被调用时，我得到了错误:

警告:尝试在 <AppName.StartScreenViewController: 0x7fae61f79980> 上呈现 <AppName.PauseScreen: 0x7fae61fe5ff0>，其 View 不在窗口层次结构中!

“StartScreenViewController”是我的开始屏幕的 View Controller ，也是初始 View Controller 。然后它转到“GameScene”，这是“PauseScreen”需要去的地方。如果我将初始 View Controller 设置为“GameViewController”/“GameScene”，它会起作用，所以我认为我需要更改第二行:

let currentViewController = (UIApplication.sharedApplication().delegate as AppDelegate)

以便它在“GameViewController”上显示“PauseScreen”，而不是在“StartScreenViewController”上显示，但我不确定该怎么做。

Answer 1

错误会准确告诉您发生了什么。

Warning: Attempt to present <AppName.PauseScreen: 0x7fae61fe5ff0> on <AppName.StartScreenViewController: 0x7fae61f79980> whose view is not in the window hierarchy!

(UIApplication.sharedApplication().delegate as AppDelegate).window?.rootViewController指向 StartScreenViewController 的实例.这很糟糕:rootViewController应该指向 GameScene 的实例.

根本原因一定是怎么来的GameScene被呈现。根据您的描述:

The "StartScreenViewController" is the view controller… It then goes to the "GameScene"…

这一定是您的问题所在。你怎么去GameScene来自 StartScreenViewController ？

我的猜测是您正在向应用程序添加一个新窗口。您需要设置 rootViewController相反。

let gameScene = UIStoryboard(name: "Main", bundle:nil).instantiateViewControllerWithIdentifier("GameSceneID") as UIViewController
let appDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
appDelegate.window?.rootViewController = gameScene

当您返回到开始屏幕时，您再次设置了 rootViewController .

let initialViewController = UIStoryboard(name: "Main", bundle:nil).instantiateInitialViewController() as UIViewController
let appDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
appDelegate.window?.rootViewController = initialViewController

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您可以使用 transitionFromViewController(,toViewController:, duration:, options:, animations:, completion:) 设置 Root View Controller 的动画。