Swift 语言的委托 [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，我在类中创建了协议和初始化委托:

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<前>class ViewController: UIViewController, testProtocol {

First Controller

但是函数没有被调用

推荐答案

我将假设您正在使用故事板.如果我是对的，那么您的问题是在您的第一个控制器中创建的 secondController 不是您所展示的实际控制器.您需要在 prepareForSegue:

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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