ios - 使用推送弹出导航在多个 View Controller 之间传递数据时出现问题

Question

我的工作是
1 .从第一个 View Controller 传递数据 -> 使用 pushViewController 的第二个 View Controller :成功

2 .Passing data from second view controller -> First View Controller using popViewController: Success//使用委托(delegate)协议(protocol)返回数据

3 .从第三个 View Controller 传递数据 -> 第一个 View Controller :错误

代码 :
ViewController.swift

import UIKit

class ViewController: UIViewController,secondViewDelegate,thirddelegate {

    @IBOutlet var Firstoutput: UILabel!

    @IBOutlet var inputField: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()
    }
    func popdata(value: String) { //second view controller delegate protocol defintions
        Firstoutput.text = "\(value)"
    }
    func thirdView(datas:String) //third view controller delegate protocol definition
    {
        print(datas)
    }
    @IBAction func pushBtn(_ sender: Any) { //first view button action

      let storyboard = UIStoryboard(name: "Main", bundle: nil)

        let vcFirst = storyboard.instantiateViewController(withIdentifier: "second") as! SecondViewController //secondview

        vcFirst.Secondtext = inputField.text

        vcFirst.delegate = self //second view delegate intiate

        let vcThird = storyboard.instantiateViewController(withIdentifier: "third") as! ThirdViewController //third view

        vcThird.thirddelegate = self //third view delegate intiate

        navigationController?.pushViewController(vcFirst, animated: true)
    }
}

SecondViewController.swift

import UIKit
//protocol for passing data when pop
protocol secondViewDelegate {
    func popdata(value:String)
}
class SecondViewController: UIViewController {

    @IBOutlet var secondOutputField: UILabel!

    @IBOutlet var secondInputField: UITextField!

    var Secondtext:String!

    var delegate:secondViewDelegate!
    override func viewDidLoad() {
        super.viewDidLoad()
        secondOutputField.text = Secondtext

    }
    //popping back to first view controller using data
    @IBAction func popBtn(_ sender: Any) {
        if delegate?.popdata != nil
        {
        delegate.popdata(value: secondInputField.text!)
        }
    navigationController?.popViewController(animated: true)
    }
    //pushing to third view controller
    @IBAction func thirdPageBtn(_ sender: Any) {
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let vcThird = storyboard.instantiateViewController(withIdentifier: "third") as! ThirdViewController
        navigationController?.pushViewController(vcThird, animated: true)
    }

}

ThirdViewController.swift

import UIKit
protocol thirdviewDelegate //delegate to pass data from thirs view to first view
{
    func thirdView(datas:String)
}
class ThirdViewController: UIViewController {

    var thirddelegate:thirdviewDelegate!

    @IBOutlet var thirdTextField: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad
    }


    @IBAction func thirdViewInvoke(_ sender: Any) {
        if thirddelegate?.thirdView != nil
        {
        thirddelegate.thirdView(datas: thirdTextField.text!)
        }
    }


}

输出截图:




仅将数据从第三个 View Controller 传递到第一个 View Controller 不起作用帮助我解决这个问题...谢谢

Answer 1

您可以使用 NotificationCenter接收数据。

按下 ThirdViewController 中的获取数据按钮，发布您的notification .

let myDataToPass : [String: Any] = ["myData" : yourStringValue]
NotificationCenter.default.post(name: Notification.Name("getDataPressed"), object: myDataToPass)

在您的 FirstViewController , 在 viewDidLoad 中添加观察者将监听 notification :

override func viewDidLoad() {
    super.viewDidLoad()
      NotificationCenter.default.addObserver(self, selector: #selector(receiveInitialDetails(notification:)), name: Notification.Name("getDataPressed"), object: nil)
}

//once the notification is received, this function will be called and you can get the data that you passed in thirdVC using notification.userInfo
@objc func receiveInitialDetails(notification : Notification) {
     let data = notification.userInfo as! [String:Any]
     let yourStringValue = data["myData"] as! String
     // you have your data here. downcast it to your desired data type.
}