用Swift语言代理 [英] Delegate in Swift-language

问题描述

我有两个控制器，我需要调用第一个控制器到第二个控制器的功能：
在第二个控制器中，我在课堂上创建了协议和init委托：

I have two controllers and i need call up function the first controller to second controller: In second controller I have created protocol and init delegate in class:

    protocol testProtocol {
        func testDelegate() // this function the first controllers
    }

    class SecondViewController: UIViewController {
        var delegate: testProtocol?
    ....
    }
    @IBAction func testDelegateClicked(sender : AnyObject) {
            delegate?.testDelegate()
        }

第一个控制器

First Controller

        class ViewController: UIViewController, testProtocol {

但是没有调用函数

推荐答案

我将假设您正在使用故事板。如果我是正确的，那么你的问题是在你的第一个控制器中创建的 secondController 不是你提出的实际的。您需要在 prepareForSegue中设置 secondController ：

I am going to make an assumption you are using storyboards. If I am correct, then your issue is that your secondController, created in your First Controller, is not the actual one you are presenting. You will need to set secondController in your prepareForSegue:

不变

class ViewController: UIViewController, testProtocol {

    // you will want to add the ? since this variable is now optional (i.e. can be nil)
    var secondController: SecondViewController? // don't assign it a value yet

    // ...

    // implementation of the protocol
    func testDelegate() {
        println("Hello delegate")
    }

    // your prepare for segue
    override func prepareForSegue(segue: UIStoryboardSegue?, sender: AnyObject?) {
        // get the controller that storyboard has instantiated and set it's delegate
        secondController = segue!.destinationViewController as? SecondViewController
        secondController!.delegate = self;
    }
}

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