uicollectionview not showing cells swift - ios

Question

I got my data from a url as json string. in my codes, titles variable is an array of my url images.
private let reuseIdentifier = "cell_supporters"
class SupportersCollectionViewController: UICollectionViewController {
var ids = [String]()
var titles = [String]()
#IBOutlet var collection_supporters: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad()
collection_supporters.delegate = self
// Register cell classes
self.collectionView!.register(UICollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)
getSupporters()
}
// MARK: UICollectionViewDataSource
// override func numberOfSections(in 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 self.titles.count
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath as IndexPath) as! SupportersCollectionViewCell
print("Hello collectionView")
let url_img = URL(string: self.titles[indexPath.row])!
print(url_img)
cell.img_logo.af_setImage(
withURL: url_img
)
return cell
}
func getSupporters() {
RestApiManager.sharedInstance.getSupporters { (json: JSON) in
if let results = json.array {
for entry in results {
// print(entry["title"])
//self.ids.append(entry["id"].string!)
self.titles.append(entry["title"].string!)
}
print(self.titles.count)
DispatchQueue.main.async{
self.collection_supporters.reloadData()
}
}
}
}
}
in my code :
print(self.titles.count) // it shows 5
but:
print("Hello collectionView") // not show anything !

Answer 1

If you're using the default UICollectionViewFlowLayout class for the layout you can try implementing the delegate method that returns the size of each item in the collectionView. The UICollectionView doesn't call the cellForItemAt dataSource method at all if it doesn't have the size information or if they're zero.
Try adding this:
extension SupportersCollectionViewController: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: 40, height: 40) // Return any non-zero size here
}
}

Answer 2

Dont register cell classes. Delete following line from viewDidLoad function :
self.collectionView!.register(UICollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)

Answer 3

Add this line in your ViewDidLoad() method:
self.collectionView!.delegate = self

Answer 4

Change it to this:
private let reuseIdentifier = "cell_supporters"
class SupportersCollectionViewController: UICollectionViewController {
var ids = [String]()
var titles = [String]()
override func viewDidLoad() {
super.viewDidLoad()
// Register cell classes
self.collectionView!.register(SupportersCollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)
getSupporters()
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of items
return self.titles.count
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath as IndexPath) as! SupportersCollectionViewCell
print("Hello collectionView")
let url_img = URL(string: self.titles[indexPath.row])!
print(url_img)
cell.img_logo.af_setImage(
withURL: url_img
)
return cell
}
func getSupporters() {
RestApiManager.sharedInstance.getSupporters { (json: JSON) in
if let results = json.array {
for entry in results {
// print(entry["title"])
//self.ids.append(entry["id"].string!)
self.titles.append(entry["title"].string!)
}
print(self.titles.count)
DispatchQueue.main.async{
self.collectionView!.reloadData()
}
}
}
}
}
First, you don't required this:
#IBOutlet var collection_supporters: UICollectionView!
Because your view controller is inherited from UICollectionViewController
Also I changed the register of the UICollectionViewCell class to this so it won't crash when you the cells are created:
self.collectionView!.register(SupportersCollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)