swift - 如何将 fetchRequest 更改为数组以在 UITableView 中使用

Question

我想把从 coredata 中获取的数据放在 UITableView 中，但我得到了这个“EXC_BAD_INSTRUCTION”。
使用 let swiftBlogs Array 工作得很好，所以有人可以告诉我如何将 fetch 转换为 Array 或者这不是正确的方法吗？

import UIKit
import CoreData

class MainViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {

    @IBOutlet var scrollView: UIScrollView!

    @IBOutlet var timeStampTextField: UITextField!
    @IBOutlet var quickQuoteTextField: UITextField!

    @IBOutlet var tableViewQuickQuote: UITableView!


    let swiftBlogs = ["Ray Wenderlich", "NSHipster", "iOS Developer Tips", "Jameson Quave", "Natasha The Robot", "Coding Explorer", "That Thing In Swift", "Andrew Bancroft", "iAchieved.it", "Airspeed Velocity"]

    var tableViewCellArray : Array<AnyObject> = []
    var quickQuoteArray : Array<AnyObject> = []


    override func viewDidLoad() {
        super.viewDidLoad()

    }


    override func viewDidAppear(animated: Bool) {
        var appDel: AppDelegate            = UIApplication.sharedApplication().delegate as! AppDelegate
        var context:NSManagedObjectContext = appDel.managedObjectContext!
        var request                        = NSFetchRequest(entityName: "QuickQuote" )
            request.returnsObjectsAsFaults = false
            tableViewCellArray             = context.executeFetchRequest(request, error: nil)!


    }

    override func viewWillAppear(animated: Bool) {
        quickQuoteTextField.text = ""
        timeStampTextField.text = ""
    }

    @IBAction func clearButton(sender: AnyObject) {
        quickQuoteTextField.text = ""
        timeStampTextField.text = ""
    }

    @IBAction func addToQuickQuoteButton(sender: AnyObject) {

        let appDel: AppDelegate            = UIApplication.sharedApplication().delegate as! AppDelegate
        let context:NSManagedObjectContext = appDel.managedObjectContext!
        let ent                            = NSEntityDescription.entityForName("QuickQuote", inManagedObjectContext: context)
        var newQuickQuote                  = QuickQuote(entity: ent!, insertIntoManagedObjectContext: context)
            newQuickQuote.quickQuote       = quickQuoteTextField.text
        context.save(nil)
    }


    @IBAction func timeStampButton(sender: AnyObject) {
        timeStamp()

        let appDel: AppDelegate            = UIApplication.sharedApplication().delegate as! AppDelegate
        let context:NSManagedObjectContext = appDel.managedObjectContext!
        let ent                            = NSEntityDescription.entityForName("Time", inManagedObjectContext: context)
        var newTime                        = Time(entity: ent!, insertIntoManagedObjectContext: context)
            newTime.time  = timeStampTextField.text
            newTime.quote = quickQuoteTextField.text
        context.save(nil)
    }


    func timeStamp (){
         timeStampTextField.text = NSDateFormatter.localizedStringFromDate(NSDate(), dateStyle: NSDateFormatterStyle.FullStyle,
         timeStyle: NSDateFormatterStyle.ShortStyle)
    }

    // MARK: - Table view data source
     func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        return 1
    }


     func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return swiftBlogs.count  // return quickQuoteArray.count
    }


    private let stampCellID: NSString = "cell"  //This is the cell itself's identifier.    
     func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCellWithIdentifier(stampCellID as String, forIndexPath: indexPath) as! UITableViewCell

        var data: NSManagedObject = quickQuoteArray[indexPath.row] as! NSManagedObject
            cell.textLabel?.text    = data.valueForKey("quickQuote") as? String


//       let row = indexPath.row
//           cell.textLabel?.text = swiftBlogs[row]

        return cell

    }


/*
     func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
        return true
    }


    func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {

        var appDel: AppDelegate            = UIApplication.sharedApplication().delegate as! AppDelegate
        var context:NSManagedObjectContext = appDel.managedObjectContext!
        if editingStyle == UITableViewCellEditingStyle.Delete {
            let tv = tableView
            context.deleteObject(quickQuoteArray.self[indexPath.row] as! NSManagedObject)
            tv.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Fade)

        }

        context.save(nil)
    }
*/

     func textFieldShouldReturn(textField: UITextField) -> Bool {
        textField.resignFirstResponder()
        return true
    }


}

Answer 1

您正在混淆数组 swiftBlogs 和 quickQuoteArray。 TableView 是否尝试访问数组元素 quickQuoteArray[indexpath.row] 取决于它是否认为索引已填充，基于 numberOfRowsInSection 的结果。在 numberOfRowsInSection 方法中，您将返回 swiftBlogs 的计数，它始终是您手动输入的 10 个左右的字符串。因此，在您的请求被执行之前，或者 View 甚至有机会为了填充其他任何内容，它会尝试显示您在 cellForRowAtIndexPath 中使用的数组中不存在的元素。

简而言之:始终在 cellForRowAtIndexPath 中使用与在 numberOfRowsInSection 中使用的数组相同的数组。在这里，您混合了两个不同的数组，quickQuoteArray 和 swiftBlogs。