解析JSON並提取圖像的URL

Question

我的代碼有問題，我已經將JSON解析為獲取圖像URL的級別。 我正在嘗試使用URL給我的圖像填充集合視圖單元格中的圖像視圖。 這是我的代碼。

import UIKit

class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {

    var media = NSDictionary()

    @IBAction func SearchBTN(_ sender: AnyObject) {
        getPictures()

    }
    @IBOutlet weak var CollectionView: UICollectionView!
    @IBOutlet weak var searchBoxTF: UITextField!



    func getPictures(){
        let url = URL(string: "http://www.flickr.com/services/feeds/photos_public.gne?tags=baseball&format=json&nojsoncallback=1")
        let session = URLSession(configuration: URLSessionConfiguration.default)
        let task = URLSession.shared.dataTask(with: url!){(data, response, error) in
            if error != nil
            {
                print("Error")
            }
            else
            {
                if let content = data
                {
                    do
                    {
                        let myJSON = try JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers) as? AnyObject
                    //print(myJSON)
                        if let images = myJSON?["items"] as? [[String: AnyObject]]
                        {
                            var media = UIImage()
                            for media in images
                            {
                               // let media = self.media
                                print(media["media"])

                            }


                        }
                    }

                    catch
                    {

                    }
                }
            }
        }
        task.resume()
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        CollectionView.delegate = self
        CollectionView.dataSource = self
        // 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.
    }


    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return media.count
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ImageCell", for: indexPath) as! ImageCollectionViewCell
        cell.imageView.image = media[indexPath.item]as? UIImage
        return cell
    }

}

Answer 1

您的JSON響應不是圖像。

cell.imageView.image = media[indexPath.item]as? UIImage cell.imageView.image = media[indexPath.item]as? UIImage ，您正在嘗試為cell.imageView.image = media[indexPath.item]as? UIImage設置JSON值。

http://www.flickr.com/services/feeds/photos_public.gne?tags=baseball&format=json&nojsoncallback=1

此URL返回JSON對具有實際圖像的 URL's響應。

然后，您需要從那些實際的圖像URL 下載UIImage 。

編輯：（基於您在評論中的問題）

1：您將獲得NSDictionary JSON Respone。

2：在NSDictionary內部，您將獲得一個帶有“ items”的NSArray ，（objectForKey：“ items”）

3：在該NSArray ，每個圖像對象都有一個對象，即NSDictionary 。

4：最后，在每個圖像對象NSDictionary都有一個名為“ media”的URL（objectForKey：“ media”），它是圖像的最終URL。 然后您需要根據該URL下載UIImage

我沒有用Swift編寫代碼，所以我不想給您錯誤的代碼示例， 有很多線程如何從JSON響應中獲取URL或任何值。

Answer 2

試試這個代碼，您將獲得預期的輸出

import UIKit

private let reuseIdentifier = "Cell"

class MCollectionViewController: UICollectionViewController {

    var arraImage: [String] = [String]()


    override func viewDidLoad() {
        super.viewDidLoad()

        // Uncomment the following line to preserve selection between presentations
        // self.clearsSelectionOnViewWillAppear = false

        self.collectionView!.backgroundColor = UIColor.whiteColor()
        RestAPIManager.sharedInstance.getServerData { (Json) -> Void in
            //print("Response = \(Json)")
            let array = Json["items"].arrayValue
            for item in array {
                print("\(item["media"]["m"])")
                self.arraImage.append(item["media"]["m"].stringValue)
                dispatch_async(dispatch_get_main_queue(), { () -> Void in
                    self.collectionView!.reloadData()
                })
            }
        }
    }


    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        // Get the new view controller using [segue destinationViewController].
        // Pass the selected object to the new view controller.
    }
    */

    // MARK: UICollectionViewDataSource

    override func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
        // #warning Incomplete implementation, return the number of sections
        return 1
    }


    override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        // #warning Incomplete implementation, return the number of items
        return arraImage.count
    }

    func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {

        let padding =  10
        let collectionViewSize = collectionView.frame.size.width - CGFloat(padding)

        return CGSizeMake(collectionViewSize/2, collectionViewSize/2)

    }
    override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {

        let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! CollectionViewCell

        if let url: NSURL = NSURL(string: arraImage[indexPath.row]) {
            cell.imageView.sd_setImageWithURL(url)
        }
        return cell
    }

    // MARK: UICollectionViewDelegate

    /*
    // Uncomment this method to specify if the specified item should be highlighted during tracking
    override func collectionView(collectionView: UICollectionView, shouldHighlightItemAtIndexPath indexPath: NSIndexPath) -> Bool {
        return true
    }
    */

    /*
    // Uncomment this method to specify if the specified item should be selected
    override func collectionView(collectionView: UICollectionView, shouldSelectItemAtIndexPath indexPath: NSIndexPath) -> Bool {
        return true
    }
    */

    /*
    // Uncomment these methods to specify if an action menu should be displayed for the specified item, and react to actions performed on the item
    override func collectionView(collectionView: UICollectionView, shouldShowMenuForItemAtIndexPath indexPath: NSIndexPath) -> Bool {
        return false
    }

    override func collectionView(collectionView: UICollectionView, canPerformAction action: Selector, forItemAtIndexPath indexPath: NSIndexPath, withSender sender: AnyObject?) -> Bool {
        return false
    }

    override func collectionView(collectionView: UICollectionView, performAction action: Selector, forItemAtIndexPath indexPath: NSIndexPath, withSender sender: AnyObject?) {

    }
    */

}

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