The Image in cell does not appear - ios

Question

I'm using alamofire to get url image from json file, and want to display the image I get from json to imageview in cell. I'm new to swift and swift networking.
My code on MainCollectionViewController:
private let reuseIdentifier = "Cell"
class MainCollectionViewController: UICollectionViewController {
var result:String = ""
override func viewDidLoad() {
super.viewDidLoad()
}
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 1
}
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! MainCollectionViewCell
Alamofire.request(.POST, "URL That Contain JSON").responseJSON { response in
if let value = response.result.value {
let json = JSON(value)
let data = json["data"].arrayValue
self.result = data[0]["image"].stringValue
print(self.result)
}
}
let imageName = (result)
cell.mainImageView.image = UIImage(named:imageName)
return cell
}
And the image outlet is in MainCollectionViewCell:
class MainCollectionViewCell: UICollectionViewCell {
#IBOutlet weak var mainImageView: UIImageView!
}
The build succeded but the image does not appear, it shows cell with no image inside.

Answer 1

Alamofire is still requesting for JSON but you have your UIImageView updated before the response arrives. Before Alamofire can come back with response, your code will try to update UIImageView with result which has not yet been received making your Result string still an empty string just like you declared on top.That is why you are getting empty UIImageView.
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! MainCollectionViewCell
Alamofire.request(.POST, "URL That Contain JSON").responseJSON { response in
if let value = response.result.value {
let json = JSON(value)
let data = json["data"].arrayValue
self.result = data[0]["image"].stringValue
print(self.result)
let imageName = (result)
cell.mainImageView.image = UIImage(named:imageName)
}
}
return cell
}
It is however not a popular practice to make load request when cell is updating.

Answer 2

Responce running in diferent thread so at that time "result" doesn't have data. try to load after the responce will solve your problem .
override func viewDidLoad() {
super.viewDidLoad()
getImage()
}
func getImage()
{
Alamofire.request(.POST, "URL That Contain JSON").responseJSON { response in
if let value = response.result.value {
let json = JSON(value)
let data = json["data"].arrayValue
self.result = data[0]["image"].stringValue
print(self.result)
}
//reload collection view
}
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! MainCollectionViewCell
let decodedData = NSData(base64EncodedString: result, options: NSDataBase64DecodingOptions(rawValue: 0))
let decodedimage = UIImage(data: decodedData!)
cell.mainImageView.image = decodedimage
return cell
}

Answer 3

In your code you didn't register your nib.
self.collectionView.registerNib(UINib(nibName: "MainCollectionViewCell", bundle: nil), forCellReuseIdentifier: "MainCollectionViewCell")
Put this code on ViewDidLoad

Answer 4

you are just getting image url not image from the server so firstly you should be download image then set in mainImageView.