我试图在视图控制器之间传递数据，但我的 16 个变量中只有一半通过？ [复制]

Question

本质上，我试图让 16 个不同的变量从一个视图控制器传递到另一个视图控制器，但只有底部的 8 个对手变量被传递。我不确定我做错了什么，或者为什么只有那 8 个专门（它们有共同的“对手”）被通过。我是 XCode 的新手，所以任何可以帮助我的东西都会很棒。打印行正在测试以查看变量是否在第一个不工作和第二个按预期工作的情况下发送。

    //
//  ThirdViewController.swift
//  rally
//
//  Created by GBernero on 12/6/16.
//  Copyright © 2016 GBernero. All rights reserved.
//

import UIKit

class ThirdViewController: UIViewController {

    @IBOutlet weak var emptyTennisCourt: UIImageView!
    @IBOutlet weak var labelOpponent: UILabel!
    @IBOutlet weak var labelPlayer: UILabel!

    var playerWinners = 0 //holds total amount of winners player has hit
    var playerShortWinners = 0 //holds amount of winners play has hit short
    var playerDeepWinners = 0 //holds amount of winners play has hit deep
    var playerErrors = 0 //holds total amount of errors play has hit
    var playerErrorsLeft = 0 //holds amount of errors play has hit left
    var playerErrorsRight = 0 //holds amount of errors play has hit right
    var playerErrorsDeep = 0 //holds amount of errors play has hit deep
    var playerErrorsNet = 0 //holds amount of errors play has hit in the net
    var opponentWinners = 0 //holds total amount of winners opponent has hit
    var opponentShortWinners = 0 //holds amount of winners opponent has hit short
    var opponentDeepWinners = 0 //holds amount of winners opponent has hit deep
    var opponentErrors = 0 //holds total amount of errors opponent has hit
    var opponentErrorsLeft = 0 //holds amount of errors opponent has hit left
    var opponentErrorsRight = 0 //holds amount of errors opponent has hit right
    var opponentErrorsDeep = 0 //holds amount of errors opponent has hit deep
    var opponentErrorsNet = 0 //holds amount of errors opponent has hit in the net

    override func prepare(for segue: UIStoryboardSegue, sender: Any?)
    {
        let dvc = segue.destination as! SixthViewController
        dvc.playerErrorsDeep = self.playerErrorsDeep
        print("segueing from self \(self.playerErrorsDeep) to dvc: \(dvc.playerErrorsDeep)")
        dvc.playerErrorsNet = self.playerErrorsNet
        dvc.playerErrorsLeft = self.playerErrorsLeft
        dvc.playerErrorsRight = self.playerErrorsRight
        dvc.playerErrors = self.playerErrors
        dvc.playerShortWinners = self.playerShortWinners
        dvc.playerDeepWinners = self.playerDeepWinners
        dvc.playerWinners = self.playerWinners
        dvc.opponentErrorsDeep = self.opponentErrorsDeep
        print("segueing to dvc2: \(dvc.opponentErrorsDeep)")
        dvc.opponentErrorsNet = self.opponentErrorsNet
        dvc.opponentErrorsLeft = self.opponentErrorsLeft
        dvc.opponentErrorsRight = self.opponentErrorsRight
        dvc.opponentErrors = self.opponentErrors
        dvc.opponentShortWinners = self.opponentShortWinners
        dvc.opponentDeepWinners = self.opponentDeepWinners
        dvc.opponentWinners = self.opponentWinners

    }

    override func viewDidLoad()
    {
        self.navigationItem.setHidesBackButton(true, animated: false) //removes back button from access by user

        self.view.backgroundColor = UIColor(patternImage: UIImage(named: "tennis_background.jpg")!) //sets background of view controller to the background image


        super.viewDidLoad()
    }

    @IBAction func youErrorDeep(_ sender: Any)
    {
        playerErrors += 1
        playerErrorsDeep += 1
        print("deep \(playerErrors), \(playerErrorsDeep)")
    }
    @IBAction func youErrorLeft(_ sender: Any)
    {
        playerErrors += 1
        playerErrorsLeft += 1
    }

    @IBAction func youErrorRight(_ sender: Any)
    {
        playerErrors += 1
        playerErrorsRight += 1
    }

    @IBAction func youWinnerDeep(_ sender: Any)
    {
        playerWinners += 1
        playerDeepWinners += 1
    }

    @IBAction func youWinnerShort(_ sender: Any)
    {
        playerWinners += 1
        playerShortWinners += 1
    }

    @IBAction func youErrorNet(_ sender: Any)
    {
        playerErrors += 1
        playerErrorsNet += 1
    }

    @IBAction func opponentErrorDeep(_ sender: Any)
    {
        opponentErrors += 1
        opponentErrorsDeep += 1
        print( "it happens")
    }

    @IBAction func opponentErrorLeft(_ sender: Any)
    {
        opponentErrors += 1
        opponentErrorsLeft += 1
    }

    @IBAction func opponentErrorRight(_ sender: Any)
    {
        opponentErrors += 1
        opponentErrorsRight += 1
    }

    @IBAction func opponentWinnerDeep(_ sender: Any)
    {
        opponentWinners += 1
        opponentDeepWinners += 1
    }

    @IBAction func opponentWinnerShort(_ sender: Any)
    {
        opponentWinners += 1
        opponentShortWinners += 1
    }

    @IBAction func opponentErrorNet(_ sender: Any)
    {
        opponentErrors += 1
        opponentErrorsNet += 1
    }




    /*
    // 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.
    }
    */


}

Answer 1

您发布了大量代码并告诉我们，当您将 print 语句替换为：

print("segueing from self \(self.playerErrorsDeep) to dvc: \(dvc.playerErrorsDeep)")

...然后显示：

从 self 0 到 dvc: 0

所以，在调用 prepareForSegue 时，问题只是出现了 playerErrorsDeep 是 0。所以问题不在于“为什么没有设置dvc 的值？”而是“为什么是playerErrorsDeep0？”

让我问这个问题：调用yourErrorDeep 的控件是否也附加了一个segue？如果您同时拥有 segue 和 @IBAction（或多个 @IBAction），则无法保证它们被调用的顺序。

您应该从按钮中删除 segue，并让 @IBAction 在完成更新值时以编程方式调用 segue，而不是让控件同时具有 @IBAction 和 segue。所以，你应该：

• 移除按钮和下一个场景之间的segue；

• 相反，通过control在视图控制器之间添加segue - 从“第三”场景上方的视图控制器图标拖动到“第六”场景：

• 选择那个segue并给它一个标识符：

• 让您的@IBAction 执行您想要的任何更新，然后以编程方式执行转场：

  @IBAction func youErrorDeep(_ sender: Any) {
      playerErrors += 1
      playerErrorsDeep += 1
      print("deep \(playerErrors), \(playerErrorsDeep)")
  
      performSegue(withIdentifier: "GoToSixth", sender: self)
  }
  

这将确保首先执行@IBAction，然后以编程方式调用segue 到下一个场景。到那时，playerErrorsDeep 将具有您期望的值。