UICollectionView cells are not displaying when API is called

Question

I'm developing a simple App which would fetch the details from the URL and it retrieves into the UICollectionViewCell. I refer many tuts' and finally I used similar to REST API. The problem is that, when it builds, no issues were found and also the UICollectionView cell becomes empty.

View Controller:

import UIKit
class ImageViewController: UIViewController, NSURLConnectionDelegate, UICollectionViewDelegate, UICollectionViewDataSource {

var items = NSMutableArray()

@IBOutlet var colView: UICollectionView!

override func viewDidLoad()
{
    super.viewDidLoad()
    self.colView!.registerClass(NSClassFromString("ImageCollectionViewCell"),forCellWithReuseIdentifier:"collectionView");
    addUrlData()
}

func addUrlData()
{
        ImageManager.sharedInstance.getRandomUser { json in

        let results: JSON = json["share"][2]["data"]

        for(key, subJson) in results
        {
            let user: NSDictionary = subJson["shares"].object as! NSDictionary
            self.items.addObject(user)
            dispatch_async(dispatch_get_main_queue(),{
                colView?.reloadData()
            })
        }  
    }
}

func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    //return self.items.count;
    return 10

}



func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let row = indexPath.row
    var cell: ImageCollectionViewCell = collectionView.dequeueReusableCellWithReuseIdentifier("collectionView", forIndexPath: indexPath) as! ImageCollectionViewCell

    if cell == []
    {
        print("UIColViewCell Error")
    }

    let user:JSON = JSON(self.items[row])
    let picURL = "http://buddysin.aumkiiyo.com/thumb/" + user["mid"]["image"].string! + "/" + " \(245)"   // Image URL
    print(picURL)
    let url = NSURL(string: picURL)
    if let data = NSData(contentsOfURL: url!)
    {
        cell.imageLabel?.text = user["name"].string
        cell.imageView?.image = UIImage(data: data)

        //   let shareItem: Shares = ImageManager.sharedInstance.imageListArray[row]
        cell.backgroundColor = UIColor.blackColor()
    }
    //  cell.imageLabel?.text = String(shareItem.latitude!)
    return cell
}


}

Image Manager:

typealias ServiceResponse = (JSON, NSError?) -> Void

class ImageManager: NSObject {
    static let sharedInstance = ImageManager()

    let baseURL = "http://buddysin.aumkiiyo.com/api/nearby/share"

    func getRandomUser(onCompletion: (JSON) -> Void) {
        let route = baseURL
        makeHTTPGetRequest(route, onCompletion: { json, err in
           onCompletion(json as JSON)     })

    }

    func makeHTTPGetRequest(path: String, onCompletion: ServiceResponse) {
        let request = NSMutableURLRequest(URL: NSURL(string: path)!)

        let session = NSURLSession.sharedSession()

        let task = session.dataTaskWithRequest(request, completionHandler: {data, response, error -> Void in
            let json:JSON = JSON(data: data!)

            onCompletion(json, error)
            if error != nil
                {
                    print("***** NSUrlSession error=\(error)")
                    return
            }

            //You can print out response object
            print("******** Response object = \(response)")

            //Print out response body
            let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)
            print("******** Response body = \(responseString)")

        })
        task.resume()
    }
    //MARK: Perform a POST Request
    func makeHTTPPostRequest(path: String, body: [String: AnyObject], onCompletion: ServiceResponse) {
        //var err: NSError?
        let request = NSMutableURLRequest(URL: NSURL(string: path)!)
        // Set the method to POST
        request.HTTPMethod = "POST"

        // Set the POST body for the request
        do {
            request.HTTPBody = try NSJSONSerialization.dataWithJSONObject(body, options: [])
            let session = NSURLSession.sharedSession()
            let task = session.dataTaskWithRequest(request, completionHandler: {data, response, error -> Void in
                let json:JSON = JSON(data: data!)
                onCompletion(json, error)
                if error != nil
                {
                    print("***** NSUrlSession error=\(error)")
                    return
                }

         //       //You can print out response object
           //     print("******** Response object = \(response)")

                //Print out response body
                let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)
                print("******** Response body = \(responseString)")


            })
            task.resume()
        } catch {
            print("error:\(error)")
        }
    }
}

The library for this app is : SwiftyJSON. Can any one help me to resolve this issue?

Answer 1

First of all, I don't see you setup the dataSource and delegate.

Try

self.colView!.dataSource = self // dataSource delegate
self.colView!.delegate = self  // UICollectionView delegate

Second, you don't have to call reloadData() every time. You just call it when your data is ready, it will reload all of it.

Another thing is, make sure JSON(self.items[row]) has the data when cellForItemAtIndexPath is called. If your HTTP request is async, call reloadData in your completion handler, like in onCompletion(json, error) if no error occurred.