Question

我使用Swift，之前我还没有遇到过这个问题。这是我的代码：

 var item = jsonResult["items"][0] as! NSDictionary

我的整行说错误

无法下标类型＆＃39;任何对象的值？＆＃39;索引类型为＆＃39; Int＆＃39;

任何帮助？

我的其余代码在这里：

import UIKit
import CoreData

class MasterViewController: UITableViewController, NSFetchedResultsControllerDelegate {
    var detailViewController: DetailViewController? = nil
    var managedObjectContext: NSManagedObjectContext? = nil


    override func awakeFromNib() {
        super.awakeFromNib()
        if UIDevice.currentDevice().userInterfaceIdiom == .Pad {
            self.clearsSelectionOnViewWillAppear = false
            self.preferredContentSize = CGSize(width: 320.0, height: 600.0)
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.



        let urlPath = "https://www.googleapis.com/blogger/v3/blogs/10861780/posts?key=AIzaSyDZ86TotGGMQpRJ6GCNrCMDMaqwbQAbfz4"

        let url = NSURL(string: urlPath)

        let session = NSURLSession.sharedSession()

        let task = session.dataTaskWithURL(url!, completionHandler: {data, response, error -> Void in

            if (error != nil) {
                println(error)
            } else {
            let jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error:nil) as!
                NSDictionary

                var item = jsonResult["items"][0] as! NSDictionary




            }

    })

        task.resume()



        if let split = self.splitViewController {
            let controllers = split.viewControllers
            self.detailViewController = controllers[controllers.count-1].topViewController as? DetailViewController
        }
    }

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

    func insertNewObject(sender: AnyObject) {
        let context = self.fetchedResultsController.managedObjectContext
        let entity = self.fetchedResultsController.fetchRequest.entity!
        let newManagedObject = NSEntityDescription.insertNewObjectForEntityForName(entity.name!, inManagedObjectContext: context) as! NSManagedObject

        // If appropriate, configure the new managed object.
        // Normally you should use accessor methods, but using KVC here avoids the need to add a custom class to the template.
        newManagedObject.setValue(NSDate(), forKey: "timeStamp")

        // Save the context.
        var error: NSError? = nil
        if !context.save(&error) {
            // Replace this implementation with code to handle the error appropriately.
            // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
            //println("Unresolved error \(error), \(error.userInfo)")
            abort()
        }
    }

    // MARK: - Segues

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if segue.identifier == "showDetail" {
            if let indexPath = self.tableView.indexPathForSelectedRow() {

                let controller = (segue.destinationViewController as! UINavigationController).topViewController as! DetailViewController

                controller.navigationItem.leftBarButtonItem = self.splitViewController?.displayModeButtonItem()
                controller.navigationItem.leftItemsSupplementBackButton = true
            }
        }
    }

    // MARK: - Table View

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

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

    override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! UITableViewCell
        cell.textLabel!.text = "Blog Item"
        return cell
    }

    override func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
        // Return false if you do not want the specified item to be editable.
        return true
    }

    override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
        if editingStyle == .Delete {
            let context = self.fetchedResultsController.managedObjectContext
            context.deleteObject(self.fetchedResultsController.objectAtIndexPath(indexPath) as! NSManagedObject)

            var error: NSError? = nil
            if !context.save(&error) {
                // Replace this implementation with code to handle the error appropriately.
                // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
                //println("Unresolved error \(error), \(error.userInfo)")
                abort()
            }
        }
    }

    func configureCell(cell: UITableViewCell, atIndexPath indexPath: NSIndexPath) {
            let object = self.fetchedResultsController.objectAtIndexPath(indexPath) as! NSManagedObject
        cell.textLabel!.text = object.valueForKey("timeStamp")!.description
    }

    // MARK: - Fetched results controller

    var fetchedResultsController: NSFetchedResultsController {
        if _fetchedResultsController != nil {
            return _fetchedResultsController!
        }

        let fetchRequest = NSFetchRequest()
        // Edit the entity name as appropriate.
        let entity = NSEntityDescription.entityForName("Event", inManagedObjectContext: self.managedObjectContext!)
        fetchRequest.entity = entity

        // Set the batch size to a suitable number.
        fetchRequest.fetchBatchSize = 20

        // Edit the sort key as appropriate.
        let sortDescriptor = NSSortDescriptor(key: "timeStamp", ascending: false)
        let sortDescriptors = [sortDescriptor]

        fetchRequest.sortDescriptors = [sortDescriptor]

        // Edit the section name key path and cache name if appropriate.
        // nil for section name key path means "no sections".
        let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: self.managedObjectContext!, sectionNameKeyPath: nil, cacheName: "Master")
        aFetchedResultsController.delegate = self
        _fetchedResultsController = aFetchedResultsController

        var error: NSError? = nil
        if !_fetchedResultsController!.performFetch(&error) {
             // Replace this implementation with code to handle the error appropriately.
             // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. 
             //println("Unresolved error \(error), \(error.userInfo)")
             abort()
        }

        return _fetchedResultsController!
    }    
    var _fetchedResultsController: NSFetchedResultsController? = nil

    func controllerWillChangeContent(controller: NSFetchedResultsController) {
        self.tableView.beginUpdates()
    }

    func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) {
        switch type {
            case .Insert:
                self.tableView.insertSections(NSIndexSet(index: sectionIndex), withRowAnimation: .Fade)
            case .Delete:
                self.tableView.deleteSections(NSIndexSet(index: sectionIndex), withRowAnimation: .Fade)
            default:
                return
        }
    }

    func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {
        switch type {
            case .Insert:
                tableView.insertRowsAtIndexPaths([newIndexPath!], withRowAnimation: .Fade)
            case .Delete:
                tableView.deleteRowsAtIndexPaths([indexPath!], withRowAnimation: .Fade)
            case .Update:
                self.configureCell(tableView.cellForRowAtIndexPath(indexPath!)!, atIndexPath: indexPath!)
            case .Move:
                tableView.deleteRowsAtIndexPaths([indexPath!], withRowAnimation: .Fade)
                tableView.insertRowsAtIndexPaths([newIndexPath!], withRowAnimation: .Fade)
            default:
                return
        }
    }

    func controllerDidChangeContent(controller: NSFetchedResultsController) {
        self.tableView.endUpdates()
    }

    /*
     // Implementing the above methods to update the table view in response to individual changes may have performance implications if a large number of changes are made simultaneously. If this proves to be an issue, you can instead just implement controllerDidChangeContent: which notifies the delegate that all section and object changes have been processed.

     func controllerDidChangeContent(controller: NSFetchedResultsController) {
         // In the simplest, most efficient, case, reload the table view.
         self.tableView.reloadData()
     }
     */

}

Answer 1

我无法确定发生了什么，因为你还没有提供太多的东西。

您没有提供将JSON数据反序列化为对象的代码。它可能是Foundation对象的集合。

听起来jsonResult是一个NSDictionary。如果是这样，每个键的值将是AnyObject类型？（可选AnyObject。）

您需要将其转换为您期望的数组类型：

if let array = jsonResult["items"] as? NSArray,
  let item = array[0] as? NSDictionary
{
  //Unwrapped the dictionary inside the array inside the dictionary.
}
else
{
  //There's something rotten in the state of Denmark
}

Answer 2

    var item = ( jsonResult["items"] as! [ NSDictionary ] )[ 0 ]

或将键限制为字符串类型：

    var item = ( jsonResult["items"] as! [ [ String: AnyObject ] ] )[ 0 ]

Answer 3

根据你得到的json，这将是多种多样的。如果你在这里发布json结果会更好。

jsonResult绝对是一个NSDictionary。但是jsonResult["item"]的类型仍然不清楚。

如果jsonResult["item"]是NSDictionary，我想没有“第一个元素”这样的说法。 NSDictionary是一个键值对，我不确定它是否有某种序列。

如果jsonResult["item"]是一个数组，你应该得到它并将其设置为NSArray。请改用let itemArray = jsonResult["item"] as! NSArray。然后你可以使用itemArray [0]来获得第一个项目。

因此，请检查jsonResult["item"]究竟是什么。

希望这有帮助。

如何从某些json中提取第一个结果？

3 个答案: