问题描述

我正在尝试将数据从 modal ViewController 传递到他的 source ViewController.我想我必须使用delegation，但它不起作用.

I'm trying to pass data from the modal ViewController to his source ViewController. I think I have to use delegation but it doesn't work.

protocol communicationControllerCamera{
    func backFromCamera()
}

class Camera: UIViewController{
    var delegate: communicationControllerCamera

    init(){
        self.delegate.backFromCamera()
    }
}


class SceneBuilder: UIViewController, communicationControllerCamera{
    func backFromCamera(){    // Never called
        println("YEAHH")
    }
}

没有调用 backFromCamera 方法.我做错了什么?

The backFromCamera method it's not called. What did I do wrong?

推荐答案

你没有设置代理，所以当你尝试调用 backFromCamera() 时它是空的.

You didn't set a delegate so it was empty when you tried to call backFromCamera().

这是一个您可以测试的简单工作示例.请注意委托的可选类型 (?) 的使用.

Here's a simple working example you can test out. Notice the use of the optional type (?) for the delegate.

// Camera class
protocol communicationControllerCamera {
    func backFromCamera()
}

class Camera: UIViewController {
    var delegate: communicationControllerCamera? = nil

    override func viewDidLoad() {
        super.viewDidLoad()
        self.delegate?.backFromCamera()
    }
}



// SceneBuilder class
class SceneBuilder: UIViewController, communicationControllerCamera {

   override func viewDidLoad() {
       super.viewDidLoad()
   }

   override func viewDidAppear(animated: Bool) {
       super.viewDidAppear(animated)

       var myCamera = Camera()
       myCamera.delegate = self

       self.presentModalViewController(myCamera, animated: true)
   }

   func backFromCamera() {
       println("Back from camera")
   }
}

您可以在 Apple 的 Swift 文档.

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