Swift：从ViewController中的tableView传递数据到另一个ViewController

Question

我试图通过使用didSelectCellAtIndexPath和prepareForSegue方法将值从选定单元格传递到下一个视图控制器，但值不是通过。

代码都ViewControllers低于显示：

import UIKit 

class MainMenu: UIViewController, UITextFieldDelegate, UITableViewDelegate, UITableViewDataSource { 

// array of the menu options 

let mainMenuOptions = ["Exercises 1", "Exercises 2", "Exercises 3"] 

// UITableView 

@IBOutlet weak var exerciseOptions: UITableView! 


override func viewDidLoad() { 
    super.viewDidLoad() 
    exerciseOptions.delegate = self 
    exerciseOptions.dataSource = self 
    // Do any additional setup after loading the view. 
} 

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

// Table configuration 

func numberOfSectionsInTableView(tableView: UITableView) -> Int { 
    return 1 
} 

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell { 
    let cellIdentifier = "ExercisesTableViewCells" 
    let cell = tableView.dequeueReusableCellWithIdentifier(cellIdentifier, forIndexPath: indexPath) as! ExercisesTableViewCell 
    cell.textLabel!.text = mainMenuOptions[indexPath.row] 
    return cell 
    } 

func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int { 
    return 3 
} 

// Segue to VC based on row selected 
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) { 

    if indexPath.row == 0{ 
     self.performSegueWithIdentifier("SegueToExercises", sender: self) 
    } 
    else if indexPath.row == 1{ 
     self.performSegueWithIdentifier("SegueToExercises", sender: self) 
    } 
    else{ 
     self.performSegueWithIdentifier("SegueToReminders", sender: self) 
    } 
} 

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) { 
    if (segue.identifier == "SegueToExercise"){ 

     let viewController = segue.destinationViewController as? ExerciseMenu 
     viewController!.mainMenuValue = exerciseOptions.indexPathForSelectedRow!.row 


    } 

} 

对于第二个视图控制器：

import UIKit 

class ExerciseMenu: UIViewController, UITextFieldDelegate, UITableViewDelegate, UITableViewDataSource { 

@IBOutlet weak var exerciseOptionsTitle: UILabel! 
@IBOutlet weak var exerciseOptionsTable: UITableView! 
@IBAction func beginWorkout(sender: AnyObject) { 
} 

// receives data from MainMenu 
var mainMenuValue: Int! 

override func viewDidLoad() { 
    super.viewDidLoad() 
    exerciseOptionsTable.delegate = self 
    exerciseOptionsTable.dataSource = self 
    // Do any additional setup after loading the view. 
} 

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


func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell { 
    let cellIdentifier = "ExerciseMenuCell" 
    let cell = tableView.dequeueReusableCellWithIdentifier(cellIdentifier, forIndexPath: indexPath) as! ExercisesTableViewCell 
    cell.textLabel!.text = String(mainMenuValue) 
    return cell 
    } 

func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int { 
    return 1 
} 

Answer 1

见this线程这种现象可能的解释。 解决问题的第一步是在您的prepareForSegue方法中设置一个断点，以确定exerciseOptions.indexPathForSelectedRow在该点上是否已为零，在这种情况下甚至发生了某种情况，即使发生了与值相关的错误（上面的链接可以提供帮助你诊断）。

尝试在您的表视图控制器中调用一个名为类似于selectedRow的属性，并在didSelectRowAtIndexPath中设置self.selectedRow = indexPath.row。这样你就有了自己的变量，比exerciseOptions.indexPathForSelectedRow更可靠。然后适当地更改prepareForSegue中的代码。所以给你完整的方法，因为我设想他们：

（作为第一视图控制器的一个属性）var selectedRow: Int?

func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) { 

    if indexPath.row == 0{ 
    self.performSegueWithIdentifier("SegueToExercises", sender: self) 
    self.selectedRow = 0 
    } 
    else if indexPath.row == 1{ 
    self.performSegueWithIdentifier("SegueToExercises", sender: self) 
    self.selectedRow = 1 

    } 
    else{ 
    self.performSegueWithIdentifier("SegueToReminders", sender: self) 
    self.selectedRow = indexPath.row 
    } 
} 


override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) { 
    if (segue.identifier == "SegueToExercise"){ 

    let viewController = segue.destinationViewController as? ExerciseMenu 
    viewController!.mainMenuValue = self.selectedRow! 


    } 
} 

免责声明：我还在学习斯威夫特，所以我就判断自选/可选的展开可能不是我不知道的技术原因，但我认为这里的整体理论是合理的。