Question

很抱歉给您带来不便，我是iOS初学者并遇到问题...

我有一个JSON，CoreData和TableView，JSON从web获取并保存在Documents-Folder中。之后，来自JSON的一些值保存在CoreData中，并且必须使用它填充TableView。 F.E.我们采取event_title ..

我有一个控制器：

import Foundation
import UIKit
import CoreLocation
import CoreData

class QuestListViewController: UIViewController, UITableViewDataSource,UITableViewDelegate {

let managedObjectContext = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext

let eventscd = [Events]()

@IBOutlet weak var questsTabBarItem: UITabBarItem!

var questCode : String = ""

var numberofcells:Int = 0

@IBOutlet weak var tableView: UITableView!

var numbers:[String] = []

override func viewDidLoad() {
    super.viewDidLoad()

    let entity = NSEntityDescription.entityForName("Events", inManagedObjectContext: managedObjectContext!)

    let events = Events(entity: entity!, insertIntoManagedObjectContext: managedObjectContext)

    var error: NSError?
    var jsonError:NSError?
    let jsonBundle = NSBundle.mainBundle()
    let jsonFolder = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0]as! String
    let jsonPath = jsonFolder.stringByAppendingPathComponent("\(self.questCode).json")

    if let data = NSData(contentsOfFile:jsonPath, options:NSDataReadingOptions.DataReadingUncached, error:&jsonError) {

        let stringData = NSString(data: data, encoding: NSUTF8StringEncoding)

        let jsonDict : NSDictionary? = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &jsonError) as? NSDictionary

        if let err = jsonError {
            println("error parsing json")
        }

        if let jsonDictionary = jsonDict {
            println("json parsed successfully")

            let json_data = JSON(jsonDictionary).arrayValue

            let id = jsonDictionary["id"]!.stringValue
            let version: AnyObject = jsonDictionary["version"]!
            let title: AnyObject = jsonDictionary["title"]!
            let description: AnyObject = jsonDictionary["description"]!
            let events_json = jsonDictionary["events"] as! NSArray
            let eventNumber: NSNumber = jsonDictionary["events"]!.count as NSNumber
            self.numberofcells = events_json.count

        }

    }


    // Do any additional setup after loading the view, typically from a nib.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}
// MARK: - Table view data source
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    tableView.deselectRowAtIndexPath(indexPath, animated: true)

    let row = indexPath.row

}

// MARK: - Set number of rows
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return self.numberofcells
}

// MARK: - Create cell
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as! UITableViewCell
    cell.backgroundColor = UIColor.clearColor()
    cell.backgroundView = UIView.new()
    cell.selectedBackgroundView = UIView.new()

    var imageView = UIImageView(frame: CGRectMake(10, 10, cell.frame.width - 0.3, cell.frame.height - 0.3))
    let image = UIImage(named: "event_list_cell.png")
    imageView.image = image
    cell.backgroundView = UIView()
    cell.backgroundView!.addSubview(imageView)
    var row = indexPath.row
    let eventsc = eventscd[indexPath.row]  /////HERE IS FATAL BREAKPOINT

//        cell.textLabel?.text = eventTable[row] as? String
    cell.textLabel?.text = eventsc.valueForKey("event_title")![row] as? String

    return cell
}

}

活动课程：进口基金会导入CoreData

@objc(Events) class Events: NSManagedObject {

    @NSManaged var title: String
    @NSManaged var event_title: String

}

和CoreMap： http://i.imgur.com/5iKwAyn.png

有错误：

On line with "let eventsc = eventscd[indexPath.row]" in Controller
Output: "fatal error: Array index out of range"

我哪里错了？

Answer 1

这是因为在viewDidLoad中您将numberOfCells设置为值＆gt;但是eventscd中没有任何内容。这就是为什么在尝试从eventscd读取值时，会得到索引超出范围错误。

理想情况下，返回的行数应为eventscd.count，并且在加载表内容之前应填充eventscd（或者在获取数据并将值添加到eventscd后重新加载表）< / p>

Answer 2

您应该使用NSFetchedResultsController填充表格视图。查看Xcode模板（New Project - ＆gt; Master-Detail - ＆gt; check＆＃34; Use Core Data＆＃34;）并检查主控制器。

这比使用数组要好得多（性能，内存，可维护性）。

填充TableView

2 个答案: