将具有屏幕视图的另一个 class 的代表设置为自己

Question

我在 iOS 编程方面相当陌生。我有这个设置：

ViewController 在 IB 上的视图，class ViewController

SecondController 在 IB 上的视图，class secondController

我有协议：

protocol SecondControllerDelegate {
    func getSomething() -> String
}

并且我在 SecondController 上有委托变量：

class secondController: UIViewController {
    var delegate: SecondControllerDelegate?
    @IBOutlet weak var labelStatus: UILabel!

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

    @IBAction func buttonTouch(sender: AnyObject) {
        labelStatus.text = delegate?.getSomething()
    }

    func try () {
        labelStatus.text = "testing"
    }
}

现在，根据到处的提示，为了让我可以在SecondController.buttonTouch()调用delegate?.getSomething()，我需要在viewController上这样设置：

class ViewController: UIViewController, SecondControllerDelegate {
    override func viewDidLoad () {
        super.viewDidLoad()
        SecondController.delegate = self
    }
    func doSomething () -> String {
        return "testing"
    }
}

但这会产生错误 'SecondController.type' does not have a member named 'delegate'。

其他一些网站说：

class ViewController: UIViewController, SecondControllerDelegate {
    var secondController = SecondController()
    override func viewDidLoad () {
        super.viewDidLoad()
        secondController.delegate = self
    }
    func doSomething () -> String {
        return "testing"
    }
}

有了这个，就没有错误了。但是如果我在第二个屏幕上做一些应该调用委托的事情，它不会调用委托，就像 SecondController 是两个不同的对象（一个是由 StoryBoard 创建的，一个是在 ViewController 中手动创建的），即本应更改为 "testing" 的 labelStatus 根本没有更改。但如果函数 try() 被调用，它就会改变。我该怎么做？

编辑：我忘了提到我使用了 NavigationController，并从第一个屏幕过渡到第二个屏幕。

Answer 1

因为您尝试学习如何在 Swift 中构建委托，所以我在下面为您编写了一个简单的委托示例

protocol SecondViewControllerDelegate {
    func didReceiveInformationFromSecondViewcontroller (information: String)
}

class ViewController: UIViewController, SecondViewControllerDelegate {

    func openSecondViewController () {
        if let secondViewControllerInstance: SecondViewController = storyboard?.instantiateViewControllerWithIdentifier("SecondViewController") as? SecondViewController {
            secondViewControllerInstance.delegate = self
            navigationController?.pushViewController(secondViewControllerInstance, animated: true)
        }
    }

    func didReceiveInformationFromSecondViewcontroller(information: String) {
        ////Here you get the information, after sendInfoToViewController() has been executed
    }

}


class SecondViewController: UIViewController {

    var delegate: SecondViewControllerDelegate?

    func sendInfoToViewController () {
        delegate?.didReceiveInformationFromSecondViewcontroller("This ist the information")
    }

}

更新

在使用 Storyboard Segues 时遵循同样的做法

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if let secondViewControllerInstance: SecondViewController = segue.destinationViewController as? SecondViewController {
            secondViewControllerInstance.delegate = self
        }
    }

将具有屏幕视图的另一个 class 的代表设置为自己

Setting delegate of another class with screen view to self

delegates

protocols

swift