UICollectionView didSelectItemAt never triggers - ios

Question

In my VC I have a view that pulls up from the bottom. I setup and add a UICollectionView in the viewDidLoad():
//Add and setup the collectionView
collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: flowLayout)
collectionView?.register(PhotoCell.self, forCellWithReuseIdentifier: "photoCell")
collectionView?.delegate = self
collectionView?.dataSource = self
collectionView?.backgroundColor = #colorLiteral(red: 0.9771530032, green: 0.7062081099, blue: 0.1748393774, alpha: 1)
collectionView?.allowsMultipleSelection = false
collectionView?.allowsSelection = true
pullUpView.addSubview(collectionView!)
pullUpView.bringSubview(toFront: collectionView!)
The UICollectionView Delegate methods are in an extension, for now in the same codefile as the VC:
//MARK: - Extension CollectionView
extension MapVC: UICollectionViewDelegate, UICollectionViewDataSource {
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return imagesArray.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "photoCell", for: indexPath) as? PhotoCell {
let imageFromIndex = imagesArray[indexPath.item]
let imageView = UIImageView(image: imageFromIndex )
cell.addSubview(imageView)
return cell
} else {
return PhotoCell()
}
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
print("selected")
//Create PopVC instance, using storyboard id set in storyboard
guard let popVC = storyboard?.instantiateViewController(withIdentifier: "popVC") as? PopVC else { return }
popVC.passedImage = imagesArray[indexPath.row]
present(popVC, animated: true, completion: nil)
}
}
The problem is that when I tap on a cell nothing happens. I've put a print statement inside the didSelectItemAt method, but that never gets printed. So, my cells never get selected or at least the didSelectItemAt method never gets triggered!
Been debugging and trying for hours, and I can't see what's wrong. Any help appreciated. Perhaps someone could open mijn project from Github to see what's wrong, if that is allowed ?
UPDATE:
Using Debug View Hierarchy, I see something disturbing: Each photoCell has multiple (many!) UIImageViews. I think that should be just one UIImageView per photoCell. I don't know what is causing this behaviour?
Debug View Hierarchy

Answer 1

I checked your code, there are few problems:
First of all you have to change your PhotoCell implementation, and add your imageView inside the class, only when the cell is created. Your cell is not loading a XIB so you have to add the imageView in init(frame:):
class PhotoCell: UICollectionViewCell {
var photoImageView: UIImageView!
override init(frame: CGRect) {
super.init(frame: frame)
setupCell()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
private func setupCell() {
photoImageView = UIImageView()
addSubview(photoImageView)
}
override func layoutSubviews() {
super.layoutSubviews()
photoImageView.frame = bounds // ensure that imageView size is the same of the cell itself
}
}
After this change, in cellForItem method you can do cell.photoImageView.image = imageFromIndex.
The problem of didSelect not called is caused by the fact your pullUpViewis always with height = 1, even if you're able to see the collectionView, it will not receive any touch.
First add an IBOutlet of the height constraint of pullUpView in your MapVc
When creating collection view, ensure the size of collection view is the same of the pullUpView, so it will be able to scroll; collectionView = UICollectionView(frame: CGRect(x: 0, y: 0, width: view.bounds.width, height: 300), collectionViewLayout: flowLayout)
Then change animateViewUp and animateViewDown to this
func animateViewUp() {
mapViewBottomConstraint.constant = 300
pullUpViewHeightConstraint.constant = 300 // this will increase the height of pullUpView
UIView.animate(withDuration: 0.5) {
self.view.layoutIfNeeded()
}
}
#objc func animateViewDown() {
cancelAllSessions()
//remove previous loaded images and urls
imagesArray.removeAll()
imageUrlsArray.removeAll()
mapViewBottomConstraint.constant = 0
pullUpViewHeightConstraint.constant = 0 // this will reset height to 0
UIView.animate(withDuration: 0.5) {
self.view.layoutIfNeeded()
}
}
By doing all of this the swipe down gesture will not work anymore because the touch is intercepted and handled by the collection view, you should handle this manually.
However I suggest you to change the online course, there are a lot of things that I don't like about this code.