如何在swift应用程序中获取keyWindow引用？ [英] How do I get the keyWindow reference in a swift app?

问题描述

在UIViewController的viewDidLoad方法中的Objective-C中我这样做是为了在我的iOS应用程序中获取keyWindow引用：

In Objective-C in the viewDidLoad method of a UIViewController I do this to get the keyWindow reference in my iOS app:

 UIWindow * keyWindow = [[UIApplication sharedApplication] keyWindow];

所以，我将这个视图控制器移植到Swift中，我在viewDidLoad调用中执行此操作：

So, I am porting this view controller into Swift and I do this one the viewDidLoad call:

let window = UIApplication.sharedApplication().keyWindow

我试图理解为什么窗口是零。当我在该行之后放置一个断点时，然后在控制台中检查窗口，我得到了这个：

I am trying to understand why the window is nil. When I put a breakpoint right after that line I then inspect window in the console and I get this:

(lldb) po window
nil

如何让窗口成为​​我的应用程序的keyWindow的有效引用在swift？

How can I get window to be a valid reference to the keyWindow of my application in swift?

推荐答案

当我在swift中搜索窗口时，我遇到了这个问题。如果你想得到窗口而不是keyWindow，试试这个：

I came to this question when I was searching for getting window in swift. If you want to get window instead of keyWindow, try this:

if let app = UIApplication.sharedApplication().delegate as? AppDelegate, let window = app.window {
    MBProgressHUD.show(text, view:window)
}

更新了Swift 3 :(感谢@Trevor）

Updated for Swift 3: (Thanks @Trevor)

if let app = UIApplication.shared.delegate as? AppDelegate, let window = app.window {
    MBProgressHUD.show(text, view:window)
}

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