Memory growing out of control when loading users photo album in UICollecitonView

I am loading the photos from a users photo album into a collection view similar to how is done in Browsing and Modifying Photo Albums | Apple Developer Documentation . I can not seem to track down why the memory is growing out of control. I use the suggested PHCachingImageManager but all that results are blurry images, freezing scrolling and the memory growing out of control until the application crashes.

In my

viewDidLoad

  PHPhotoLibrary.requestAuthorization { (status: PHAuthorizationStatus) in
  print("photo authorization status: \(status)")
  if status == .authorized && self.fetchResult == nil {
  print("authorized")

  let fetchOptions = PHFetchOptions()
  fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)]
  var tempArr:[PHAsset] = []
  self.fetchResult = PHAsset.fetchAssets(with: .image, options: fetchOptions)

  guard let fetchResult = self.fetchResult else{
  print("Fetch result is empty")
  return
  }

  fetchResult.enumerateObjects({asset, index, stop in
  tempArr.append(asset)
  })
// self.assets = tempArr

  self.imageManager.startCachingImages(for: tempArr, targetSize: PHImageManagerMaximumSize, contentMode: .aspectFill, options: nil)

  tempArr.removeAll()
  print("Asset count after initial fetch: \(self.assets?.count)")

  DispatchQueue.main.async {
  // Reload collection view once we've determined our Photos permissions.
  print("inside of main queue reload")
  PHPhotoLibrary.shared().register(self)
  self.collectionView.delegate = self
  self.collectionView.dataSource = self
  self.collectionView.reloadData()
  }
  } else {
  print("photo access denied")
  self.displayPhotoAccessDeniedAlert()
  }
  }

and inside of

cellForItemAt:

cellForItemAt

guard let fetchResult = self.fetchResult else{
  print("Fetch Result is empty")
  return UICollectionViewCell()
  }

  let requestOptions = PHImageRequestOptions()
  requestOptions.isSynchronous = false
  requestOptions.deliveryMode = .highQualityFormat
  //let scale = min(2.0, UIScreen.main.scale)
  let scale = UIScreen.main.scale
  let targetSize = CGSize(width: cell.bounds.width * scale, height: cell.bounds.height * scale)

// let asset = assets[indexPath.item]
  let asset = fetchResult.object(at: indexPath.item)
  let assetIdentifier = asset.localIdentifier

  cell.representedAssetIdentifier = assetIdentifier

  imageManager.requestImage(for: asset, targetSize: cell.frame.size,
  contentMode: .aspectFill, options: requestOptions) { (image, hashable) in
  if let loadedImage = image, let cellIdentifier = cell.representedAssetIdentifier {

  // Verify that the cell still has the same asset identifier,
  // so the image in a reused cell is not overwritten.
  if cellIdentifier == assetIdentifier {
  cell.imageView.image = loadedImage
  }
  }
  }