ios - 在 TableViewController 和 ViewController 之间进行委托(delegate)

Question

我在 iOS 开发的第一周就遇到了在 View Controller 之间传递数据的问题。我的设置包括一个带有 VC 的 View ，其中有一个按钮，还有一个容器 View (没有关联的 View Controller )。容器 View 使用 TableViewController 嵌入了到 TableView 的 Segue。该表有 6 行，每行都有一个步进器，可以更改关联行上 TextView 的值。我想做的是在我按下主视图上的按钮时收集所有 TextView 的值。

我正在尝试使用委托(delegate)来执行此操作，但是当我按下按钮时，返回值始终为零。我认为问题在于 VC 没有通过 prepareForSegue 函数传递给 TableView Controller ，但我不确定为什么？可能与 Controller 的加载顺序有关？

import UIKit

class PredictionViewController: UIViewController, PredictionDelegate {

    var predictionData: String!

    @IBOutlet weak var messageTextBox: UITextView!
    @IBOutlet weak var predictionSubmitButton: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.

        self.messageTextBox.isEditable = false
    }

    override func viewDidAppear(_ animated: Bool) {

    }

    func prepareForSegue(segue: UIStoryboardSegue!, sender: AnyObject!) {
        if (segue.identifier == "predictionSegue") {
            // pass data to next view
            let vc = segue.destination as! PredictionsTableViewController
            vc.predictionHomeDelegate = self
        }
    }

    func receiveData(with data: String) {
        predictionData = data
        print(predictionData)
    }

    @IBAction func predictionSubmitButtonAction(_ sender: UIButton) {
        print(predictionData)
    }

}

TableViewController:(剥离到最小)

import UIKit

protocol PredictionDelegate: class {
    func receiveData(with data: String)
}

class PredictionsTableViewController: UITableViewController, PredictionDelegate {

    weak var predictionHomeDelegate: PredictionDelegate?

    @IBOutlet weak var homeTeamScore1: UITextView!
    @IBOutlet weak var homeTeamStepper1: UIStepper!

    override func viewDidLoad() {
        super.viewDidLoad()

    }

    override func viewDidAppear(_ animated: Bool) {

    }

    func getPredictionList() {
        //does some stuff
        self.passDataBackwards()
    }

    func receiveData(with data: String) {}

    func passDataBackwards() {
        let data = "{\"score\":\"1\"}"
        predictionHomeDelegate?.receiveData(with: data)
    }

    @IBAction func homeTeamStepper1Action(_ sender: UIStepper) {

        let score = Int(sender.value).description
        homeTeamScore1.text = score
        self.passDataBackwards()
    }
}

感谢收到的任何帮助!

Answer 1

编辑:

评论后...

您对协议(protocol)和委托(delegate)有错误的看法。这里不需要它们。

相反，在您的“家庭”VC 中，获取对嵌入式 VC 的引用。然后，在您的嵌入式 VC 中添加一个函数，您可以调用该函数来获取其数据。

// "home" view controller
class PredictionViewController: UIViewController {

    // this will be a reference to the embedded view controller
    var embeddedVC: PredictionsTableViewController?

    @IBAction func getDataButtonTapped(_ sender: Any) {
        if let tableData = embeddedVC?.getMyData() {
            print("Result: \(tableData)")
        }
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if (segue.identifier == "predictionSegue") {
            if let vc = segue.destination as? PredictionsTableViewController {
                // get a reference to the embedded VC
                self.embeddedVC = vc
            }
        }
    }

}

// embedded view controller
class PredictionsTableViewController: UIViewController {

    var numTaps = 0

    func getMyData() -> String {
        return "\(numTaps)"
    }

    @IBAction func didTap(_ sender: Any) {
        numTaps += 1
    }

}

你很接近，但有几个错误...

这是一个非常非常简单的例子。带容器的 View Controller ，它有一个带按钮的 View Controller 。

代码:

import UIKit

// your protocol    
protocol PredictionDelegate: class {
    func receiveData(with data: String)
}

// embedded view controller
// NOTE: this should NOT include PredictionDelegate
class PredictionsTableViewController: UIViewController {

    weak var predictionHomeDelegate: PredictionDelegate?

    @IBAction func didTap(_ sender: Any) {
        // on button tap, "send data back"
        predictionHomeDelegate?.receiveData(with: "Test")
    }

}

// "home" view controller
// NOTE: this DOES include PredictionDelegate
class PredictionViewController: UIViewController, PredictionDelegate {

    func receiveData(with data: String) {
        print(data)
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if (segue.identifier == "predictionSegue") {
            if let vc = segue.destination as? PredictionsTableViewController {
                // set self as the delegate of the embedded PredictionsTableViewController
                vc.predictionHomeDelegate = self
            }
        }
    }

}

注意事项:

• 不要在您的嵌入式 View Controller 中包含 func receiveData(with data: String) {}
• 不要将 PredictionDelegate 分配给您的嵌入式 View Controller