Swift:如何从视图控制器访问 AppDelegate 变量? [英] Swift: How to access in AppDelegate variable from the View controller?

问题描述

我想在文本或 csv(首选)文件中写入视图控制器中的变量.

I would like to write in the text or csv (prefer) file the variable from the view controller.

事实上，我正在做一个绘图应用程序，我想在文件中写入手指的当前位置.

Indeed I am doing a drawing app and I would like to write in the file the current position of the finger.

class ViewController: UIViewController {var lastPoint = CGPoint.zeroPoint ... }

我想从 AppDelegate 访问 lastPoint.x 和 lastPoint.y.我怎么能那样做?谢谢.

I would like to have access to lastPoint.x and lastPoint.y from the AppDelegate. how I could do that ? Thank you.

推荐答案

你的问题充满了困惑，但如果这就是你要找的:

Your question is full of confusion but if that's what you are looking for:

您可以通过获取对 appDelegate 的引用来访问它:

let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate

之后，如果您在 appDelegate 中存储了一个名为 lastPoint 的属性，您就可以非常简单地访问它的组件:

after that if you have store a property called lastPoint in your appDelegate you can access its components very simply like that:

let x = appDelegate.lastPoint.x
let y = appDelegate.lastPoint.y

如果您需要从 AppDelegate 访问您的 viewController 属性，那么我建议在您的 appdelegate 中引用您的视图控制器:

var myViewController: ViewController!

然后当你的视图控制器被创建时，你可以在 appdelegate 属性中存储对它的引用:

then when your view controller is created you can store a reference to it in the appdelegate property:

如果您在 appDelegate 之外创建视图控制器:

If your create your view controller outside of your appDelegate:

Swift 1-2 语法

var theViewController = ViewController()
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
appDelegate.myViewController = theViewController

Swift 3-4 语法

var theViewController = ViewController()
let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.myViewController = theViewController

如果您在 appDelegate 内创建视图控制器:

If you create your view controller inside of your appDelegate:

self.myViewController = ViewController()

之后，您只需像这样访问它的属性，就可以从您的 appdelegate 从您的视图控制器访问您的数据:

After that you can access your data from your viewcontroller from your appdelegate just by accessing its property like that:

let x = self.myViewController.lastPoint.x
let y = self.myViewController.lastPoint.y

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