UICollectionView is not loading cell second time - ios

Question

I am using UICollectionview to list some image as usual.
Code is simply getting data from api and update UICollectionView asynchronously. End of the API call code is updating data with self.collectionView?.reloadData().
Also when user scrolls to bottom of UICollectionView api call is triggered again and update photos array and collectionview data. But at this second action is not adding new cells to UICollectionView
Here is code:
class PhotoStreamViewController: UICollectionViewController {
var photos = [Photo]()
var pageIndex = 1
...
override func viewDidLoad() {
super.viewDidLoad()
allPhotos()
...
}
override func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
pageIndex+=1
allPhotos()
}
func allPhotos() {
let headers: HTTPHeaders = [
"Authorization": "Client-ID APIKEY"
]
var json:JSON = JSON()
Alamofire.request("https://www.apiurl.com/photos?page=\(pageIndex)&per_page=15&order_by=latest",method: .get, parameters: nil , encoding: URLEncoding.default, headers: headers)
.responseJSON() { (response:DataResponse<Any>) in
// debugPrint(response)
switch response.result {
case .success(let value):
json = JSON(value)
for (_,subJson):(String, JSON) in json {
let image = UIImage(data: try! Data(contentsOf: URL(string: subJson["urls"]["small"].stringValue)!))
if let photo = Photo(userName: subJson["user"]["name"].stringValue,comment: "dummy",image: image!,location: "Location",thumb: "thumb") {
self.photos.append(photo)
}
}
self.collectionView?.reloadData()
case .failure(let error):
print(error)
}
}
}
}
extension PhotoStreamViewController : UICollectionViewDelegateFlowLayout{
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return self.photos.count
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "AnnotatedPhotoCell", for: indexPath as IndexPath) as! AnnotatedPhotoCell
cell.photo = photos[indexPath.item]
return cell
}
}

Answer 1

You need to reload your collection view in main queue.Please try this.I think it's solve your problem
DispatchQueue.main.async {
self.collectionView?.reloadData()
}

Answer 2

Problem solved after add this code under self.photos.append(photo)
if(self.pageIndex > 1){
let indexPath = IndexPath(item:self.photos.count-1, section: 0)
self.collectionView?.insertItems(at: [indexPath])
}
Also i had extension like :
extension PhotoStreamViewController : PinterestLayoutDelegate
after customize layoutattributes inside PinterestLayout it worked well
override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes?

Answer 3

try this
if let layout = self.IBcollection?.collectionViewLayout as? PInterestLayout
{
layout.cache = []
layout.columnsYoffset = []
layout.contentSize = CGSize.zero
}
self.IBcollection.reloadData()

Answer 4

open PinterestLayout.
check prepare function. it containes below line. where cache is empty. whenever it reload it will get cache empty.
guard cache.isEmpty == true,let collectionView = collectionView else {return}
Replace above code with this:
guard let collectionView = collectionView else {return}
cache.removeAll() // Add this line while changing in array elements.