ios - 在主视图 Controller 中单击后更新外部 View Controller 中的 UITextField

Question

当设备通过 HDMI 连接时，我试图在 MainViewController 上显示一个按钮，在 ExternalViewController 中显示一个 UITextField。当在 MainViewController 中发生单击时，我需要更新 ExternalViewController 中的 UITextField。我可以在输出窗口中看到打印，但文本字段没有更新。

MainViewController.swift

import UIKit
import WebKit

class MainViewController: UIViewController {
  fileprivate var externalWindow: UIWindow?

  override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
    if UIScreen.screens.count > 1 {
      setupExternalScreen(UIScreen.screens[1])
    }

    let button = UIButton(frame: CGRect(x: 100, y: 100, width: 100, height: 50))
    button.backgroundColor = UIColor.blue

    button.setTitle("Click Me", for: UIControlState.normal)
    button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)

    self.view.addSubview(button)

  }

  override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
  }


  /*
   // MARK: - Navigation

   // In a storyboard-based application, you will often want to do a little preparation before navigation
   override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
   // Get the new view controller using segue.destinationViewController.
   // Pass the selected object to the new view controller.
   }
   */
  fileprivate func setupExternalScreen(_ screen: UIScreen) {
    guard externalWindow == nil,
      let vc = self.storyboard?.instantiateViewController(withIdentifier: "ExternalScreen") as? ExternalViewController else {
        return
    }

    externalWindow = UIWindow(frame: screen.bounds)
    externalWindow!.rootViewController = vc
    externalWindow!.screen = screen
    externalWindow!.isHidden = false
  }

  func buttonAction(sender: UIButton) {
    print("Button tapped")
    ExternalViewController().updateLabel()
  }

}

外部 View Controller .swift

import UIKit

class ExternalViewController: UIViewController {

    let output = UITextField(frame: CGRect(origin: CGPoint(x: 0,y :0), size: CGSize(width: 300, height: 100)))

    override func viewDidLoad() {
        super.viewDidLoad()
        self.addTextField()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func addTextField() {
      output.textColor = UIColor.black
      output.text = "This is the other text field"
      view.addSubview(output)
    }

    func updateLabel() {
      print("inside updateLabel")
      output.text = "button was clicked"
    }

}

这是它的样子。

这是我使用 Swift 的第一个项目，所以如果这是一个糟糕的问题，我深表歉意。

Answer 1

尝试使用 NotificationCentre 。 在外部VC中

override func viewDidLoad() {
    super.viewDidLoad()
     NotificationCenter.default.addObserver(self, selector: #selector(receivedDataFromNotification(notification:)), name: NSNotification.Name(rawValue: "passdata"), object: nil)
    }

   func receivedDataFromNotification(notification : NSNotification) -> Void {
        print(notification.object);
      output.text = "button was clicked"
    }

在主视图 Controller 中

NotificationCenter.default.post(name: NSNotification.Name(rawValue: "passdata"), object: "your string pass here")