Question

我的代码如下。当我按下＆＃39;完成＆＃39;或者＆＃39;取消＆＃39;按钮，它不会按我的意愿工作。我做了一些调试，delegate即{I} nil即使我设置了它。请帮忙 - 谢谢。

class ViewController: UIViewController,EditViewControllerDelegate {

    @IBOutlet weak var label: UILabel!

    //页面跳转时
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if segue.identifier == "EditView" {
            //通过seque的标识获得跳转目标
            let controller = segue.destinationViewController as! EditViewController
            //设置代理
            controller.delegate = self
            //将值传递给新页面
            controller.oldInfo = label.text
        }
    }

    func editInfo(controller:EditViewController, newInfo:String){

        label.text = newInfo
        //关闭编辑页面
        controller.presentingViewController!.dismissViewControllerAnimated(true, completion: nil)
    }

    func editInfoDidCancer(controller:EditViewController){

        //关闭编辑页面
        controller.presentingViewController!.dismissViewControllerAnimated(true, completion: nil)
    }
}

import UIKit

protocol EditViewControllerDelegate {
    func editInfo(controller:EditViewController, newInfo:String)
    func editInfoDidCancer(controller:EditViewController)
}

class EditViewController: UIViewController {

    @IBOutlet weak var textField: UITextField!

    var delegate:EditViewControllerDelegate?

    var oldInfo:String?

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        if oldInfo  != nil{
            textField.text = oldInfo
        }
    }

    @IBAction func done(sender: AnyObject) {
        delegate?.editInfo(self, newInfo: textField.text!)
    }

    @IBAction func cancel(sender: AnyObject) {
        delegate?.editInfoDidCancer(self)
    }
}

Answer 1

我无法从您的代码中了解您如何处理EditViewController中ViewController的开头。

我猜测您的prepareForSegue:sender: 未被调用，导致代理未设置。要解决此问题，您需要在performSegueWithIdentifier:sender:处添加self.performSegueWithIdentifier("EditView", sender: self)在

中需要发生segue的点

EditViewController

您应该用该呼叫替换正在执行showViewController:sender:开放的任何代码。

我有一个应用程序使用Show从第一个视图控制器打开第二个视图控制器，即使我的故事板中定义了prepareForSegue:sender: segue。我的故事板中的segue在这种情况下不会被使用，showViewController(myVC, sender: self)永远不会被调用。

如果我替换

performSegueWithIdentifier("mySegue", sender: self)

与

prepareForSegue:sender:

然后prepareForSegue:sender:将被调用。如果我在seen中设置了一个委托，那么委托将在segue发生之前设置。

Answer 2

试试这个，

class ViewController: UIViewController,EditViewControllerDelegate {
var controller: EditViewController?
    @IBOutlet weak var label: UILabel!

    //页面跳转时
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if segue.identifier == "EditView" {
            //通过seque的标识获得跳转目标
            controller = segue.destinationViewController as! EditViewController
            //设置代理
            controller.delegate = self
            //将值传递给新页面
            controller.oldInfo = label.text
        }
    }

    func editInfo(controller:EditViewController, newInfo:String){

        label.text = newInfo
        //关闭编辑页面
        controller.presentingViewController!.dismissViewControllerAnimated(true, completion: nil)
    }

    func editInfoDidCancer(controller:EditViewController){

        //关闭编辑页面
        controller.presentingViewController!.dismissViewControllerAnimated(true, completion: nil)
    }
}

import UIKit

protocol EditViewControllerDelegate {
    func editInfo(controller:EditViewController, newInfo:String)
    func editInfoDidCancer(controller:EditViewController)
}

class EditViewController: UIViewController {

    @IBOutlet weak var textField: UITextField!

    var delegate:EditViewControllerDelegate?

    var oldInfo:String?

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        if oldInfo  != nil{
            textField.text = oldInfo
        }
    }

    @IBAction func done(sender: AnyObject) {
        delegate?.editInfo(self, newInfo: textField.text!)
    }

    @IBAction func cancel(sender: AnyObject) {
        delegate?.editInfoDidCancer(self)
    }
}

View Controller委托返回nil

2 个答案: