用Swift语言代表

Question

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init委托:

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

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

第一控制器

        class ViewController: UIViewController, testProtocol {


        var secondController: SecondViewController = SecondViewController()

        override func viewDidLoad() {
            super.viewDidLoad()

            secondController.delegate = self
        }
        func testDelegate() {
            println("Hello delegate")
        }</pre>

但功能没有被调用

Answer 1

我假设您正在使用故事板.如果我是正确的,那么您的问题是您secondController在第一个控制器中创建的不是您提供的实际控制器.你需要设置secondController你的prepareForSegue:

第二控制器

不变

第一控制器

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;
    }
}