Dynamically sizing UICollectionViewCell dynamically with image upload Swift

Question

I'd like to know the best way to resize a UICollectionViewCell's dimensions dynamically(Swift 3). I have asynchronous image uploading to a ViewController which implements the appropriate protocols for UICollectionView. The images will all be different sizes, so I will need to set the cell dimensions after loading the UIImageView data. I'm open to options for the layout of the collectionview itself, but first I want to get the cell dimensions correct.

I know there are a few posts already that are similar, but I'd like to know the most appropriate way to do this in Swift 3 and I can't quite find the right way yet.

Is it possible to do the resizing dynamically in the func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {} method? Or, is there an autoresize option I can set when loading the whole view?

Here's my relevant methods at the moment, all static sizing of the CollectionView:

override func viewDidLoad() {
        super.viewDidLoad()
        ExitNameLabel.text = exitName
        let layout:UICollectionViewFlowLayout = UICollectionViewFlowLayout()
        layout.itemSize = CGSize(width: 120 , height: 120)
        self.imagesCollectionView.setCollectionViewLayout(layout, animated: true)
        exitLocationDetails.text = exitLocation
        imagesCollectionView.delegate = self
        imagesCollectionView.dataSource = self
    }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int
    {
        return imageUrls.count
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell:ImageCollectionViewCell = imagesCollectionView.dequeueReusableCell(withReuseIdentifier: "imageCell", for: indexPath) as! ImageCollectionViewCell

        if (images_cache[imageUrls[indexPath.row]] != nil) {
            cell.imageCell.image = images_cache[imageUrls[indexPath.row]]
        } else {
            loadImage(imageUrls[indexPath.row], imageview:cell.imageCell)
        }
        return cell
    }


    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }

    func collectionView(collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
        let screenSize: CGRect = UIScreen.main.bounds
        let width = screenSize.width
        return CGSize(width: CGFloat(width), height: imagesCollectionView.bounds.size.height)
    }

Thanks for helping out an iOS newbie :)

Hüseyin Hüseyin · Accepted Answer · 2017-02-12T09:30:52

try this

if (images_cache[imageUrls[indexPath.row]] != nil) {
    cell.imageCell.image = images_cache[imageUrls[indexPath.row]]
    cell.imageCell.contentMode = .scaleAspectFit
} else {
    loadImage(imageUrls[indexPath.row], imageview:cell.imageCell)
}

Dynamically sizing UICollectionViewCell dynamically with image upload Swift

1 Answers