Error when peeking and popping from collection view - swift

Question

Received an error
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)
when trying to peek and pop from a collection view. I've checked my data struct and index path but everything seems to be fine.
Here's my code for the collections view
class thisSeaonViewController: UICollectionViewController, UIViewControllerPreviewingDelegate {
#IBOutlet weak var activityIndicator: UIActivityIndicatorView!
var URLArrayStringThisSeason = [String]()
var currentURL = String()
override func viewDidLoad() {
generateData()
if( traitCollection.forceTouchCapability == .available){
registerForPreviewing(with: self as! UIViewControllerPreviewingDelegate, sourceView: view)
}
}
override func viewDidAppear(_ animated: Bool) {
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)
let imageView = cell.viewWithTag(1) as! UIImageView
let url = NSURL(string: URLArrayStringThisSeason[indexPath.row])
let placeholderImage = UIImage(named: "Rectangle")!
let filter = AspectScaledToFillSizeWithRoundedCornersFilter(
size: imageView.frame.size,
radius: 0
)
imageView.af_setImage(withURL: url as! URL, placeholderImage: placeholderImage, filter: filter, imageTransition: .crossDissolve(0.2)
)
cell.backgroundColor = UIColor.init(hexString: "#F3F3F3")
cell.layer.cornerRadius = 3.0
return cell
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return URLArrayStringThisSeason.count
}
override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
let vc = storyboard?.instantiateViewController(withIdentifier: "gridDetailedView") as! gridDetailedViewController
vc.imageURL = URLArrayStringThisSeason[indexPath.row]
self.navigationController?.pushViewController(vc, animated: true)
}
func generateData() {
if URLArrayStringThisSeason.count == 0 {
self.activityIndicator.isHidden = false
self.activityIndicator.startAnimating()
}
let queryThisSeason = FIRDatabase.database().reference().child("thisSeason")
queryThisSeason.keepSynced(true)
queryThisSeason.observeSingleEvent(of: .value, with: {(snapshot) in
if snapshot.childrenCount != 0 {
let urlArray = snapshot.value as! [String]
let urlLimitedArray = Array(urlArray.reversed())
self.URLArrayStringThisSeason = urlLimitedArray
self.collectionView?.reloadData()
self.activityIndicator.stopAnimating()
self.activityIndicator.isHidden = true
}
})
}
func previewingContext(_ previewingContext: UIViewControllerPreviewing, viewControllerForLocation location: CGPoint) -> UIViewController? {
guard let indexPath = collectionView?.indexPathForItem(at: location) else { return nil }
guard let cell = collectionView?.cellForItem(at: indexPath) else { return nil }
guard let detailVC = storyboard?.instantiateViewController(withIdentifier: "gridDetailedView") as? gridDetailedViewController else { return nil }
//let photo = UIImage(named: "Rectangle")
detailVC.imageURL = URLArrayStringThisSeason[indexPath.row]
print(URLArrayStringThisSeason[indexPath.row])
detailVC.preferredContentSize = CGSize(width: 300, height: 300)
previewingContext.sourceRect = cell.frame
print("peek")
return detailVC
}
func previewingContext(_ previewingContext: UIViewControllerPreviewing, commit viewControllerToCommit: UIViewController) {
self.navigationController?.show(viewControllerToCommit, sender: Any?.self)
print("pop")
}
}
when peeking and popping, the function is supposed to send the imageURL to the detailed view controller and AlamofireImage will handle the image download and loading.
However, I've been getting misalignment issues with the collections view as the source rect will appear slightly above the cells and preventing peek and pop at certain parts of the cell. I think that this could be the cause of the peek and pop crash too.
edit:
here's what happens when I try to do peek and pop, you can see the focus of the cell is slightly shifted on top.

Answer 1

Ok I fixed the misalignment problem by changing this registerForPreviewingWithDelegate(self, sourceView: view)
to this
registerForPreviewingWithDelegate(self, sourceView: self.collectionView!)
however, the app is still crashes everytime I try to peek and pop.
Edit:
Ok the other problem is pretty much just some errors in the code. Just follow the above to fix the misalignment problem.