协议委托方法不在Swift中调用

协议委托方法不被称为..

第一视图控制器代码

class ViewController: UIViewController,customDelegate { var seconviewcontroller : SecondViewController = SecondViewController() @IBOutlet weak var Label: UILabel! override func viewDidLoad() { super.viewDidLoad() seconviewcontroller.delegate = self } func didSelectData(_ result: String) { Label.text = result print("Didselect Data Call") } 

第二个视图控制器代码

 import UIKit protocol customDelegate: class { func didSelectData(_ result: String) } class SecondViewController: UIViewController { var delegate: customDelegate? @IBOutlet weak var secondbutton: UIButton! override func viewDidLoad() { super.viewDidLoad() } @IBAction func secondbuttonclick(_ sender: Any) { let selectedItem = "naga" delegate?.didSelectData(selectedItem) } 

如何调用函数didSelectData请帮助我

Answer 1

所以基本上在行var seconviewcontroller : SecondViewController = SecondViewController()是不同于你的推视图控制器实例。

你正在做一个SecondViewController的独立实例，所以你已经完成委托自己在推挤的时候像这样的对象

 let secondVCInstance = self.storyboard?.instantiateViewController(withIdentifier: "SecondViewController") as! SecondViewController secondVCInstance.delegate = self self.navigationController?.pushViewController(secondVCInstance, animated: true) 

注意： – 每个对象都有自己的属性

Answer 2

正如你已经使用segue在视图之间进行导航。 你也可以用这个例子。 我将以下内容作为代码示例，以便您可以跟踪自己以在代码中检测问题。

第一视图控制器

 import UIKit class ViewController: UIViewController, SecondVCDelegate { @IBOutlet weak var label: UILabel! override func viewDidLoad() { super.viewDidLoad() } override func prepare(for segue: UIStoryboardSegue, sender: Any?) { if let secondVC = segue.destination as? SecondViewController { secondVC.delegate = self } } func didSelectData(_ result: String) { label.text = result print(result) } } 

第二视图控制器

 import UIKit protocol SecondVCDelegate: class { func didSelectData(_ result: String) } class SecondViewController: UIViewController { @IBOutlet weak var button: UIButton! weak var delegate: SecondVCDelegate? override func viewDidLoad() { super.viewDidLoad() } @IBAction func buttonTapped(_ sender: UIButton) { delegate?.didSelectData("My result") dismiss(animated: true, completion: nil) } }