Swift: download image from Internet and cache them doesn't work properly. need suggestions

Question

I am new to swift, and I am building an App that download images from the Internet and display in a UICollectionView, I can achieve this function successfully, however, it seems

Answer 1

Use AlamofireImage

Swift 2.2 or 2.3

Add --> pod 'AlamofireImage', '~> 2.5' in your pod file.

Swift 3.1

Add --> pod 'AlamofireImage', '~> 3.3' in your pod file.

Put the following line in your code which will automatically cache the image and download it as well.

override func viewDidLoad() {
     super.viewDidLoad()
     //hit your web service here to get all url's
 }

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


func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell
{ 
   cell.imgViewPhoto.af_setImageWithURL(arrImageURL[indexPath.row], placeholderImage: UIImage())
}