ios - 自定义协议(protocol)委托(delegate)方法不调用

Question

我正在尝试使用自定义协议(protocol)从另一个 View Controller 更改一个 View Controller 的标签，但未调用其委托(delegate)方法

ViewController3代码:

当我点击关闭按钮时，它的委托(delegate)方法没有在我的 ViewController2 中被调用。

protocol ViewController3Delegate: class {

  func changeLable(_ text: String)
}

class ViewController3: UIViewController {

  weak var delegate: ViewController3Delegate?

  override func viewDidLoad() {
    super.viewDidLoad()

  }

  override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()

  }

  @IBAction func btnCloseAction(_ sender: Any) {

    delegate?.changeLable("fillter applied")
    self.dismiss(animated: true, completion: nil)
  }
}

ViewController2代码:

class ViewController2: UIViewController,ViewController3Delegate {

  @IBOutlet weak var lblReport: UILabel!

  let VC3 = ViewController3(nibName: "ViewController3", bundle: nil)

  override func viewDidLoad() {

    super.viewDidLoad()
    VC3.delegate = self
  }

  func changeLable(_ text: String) {

    print("delegate called")
  }

  override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()

  }
}

谁知道我哪里错了，请给我一些解决方案

Answer 1

您尚未在 ViewController2 中定义委托(delegate)，该委托(delegate)将用于 ViewController3 中的委托(delegate)。

看这个:

 protocol ViewController3Delegate: class {

      func changeLable(_ text: String)
    }

    class ViewController3: UIViewController {

      weak var delegate: ViewController3Delegate?

      override func viewDidLoad() {
        super.viewDidLoad()

      }

      override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()

      }

      @IBAction func btnCloseAction(_ sender: Any) {
        if delgate !=nil {

        delegate?.changeLable("fillter applied")
        self.dismiss(animated: true, completion: nil)
    }
      }
    }

然后在您的 ViewController2 类中:

    class ViewController2: UIViewController,ViewController3Delegate {

      @IBOutlet weak var lblReport: UILabel!


      override func viewDidLoad() {

        super.viewDidLoad()
      }

      func changeLable(_ text: String) {

        print("delegate called")
      }

      override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()

      }
          override func prepare(for segue: UIStoryboardSegue, sender: Any?) 
             {

                 if segue.identifier = "Yoursegueientifier"
                  {
                     let vc = segue.destination as! ViewController3
                     vc.delegate = self
                  }                
            }
    }

注意:您必须在 Storyboard中定义您的 segueidentifer 名称