UICollectionView cells with round photographs plus rotation assist

Round cells inside a set view

Attaining the aim is comparatively simple, however should you don’t know what’s occurring within the background it’s going to be more durable than you’ll assume first. So let’s create a brand new mission add a storyboard with a UICollectionViewController, drag a UIImageView contained in the cell, resize it, add some constraints, set the cell identifier.

It ought to look one thing just like the picture above. Nothing particular only a easy UI for our instance utility. Now seek for some random picture, add it to the mission and let’s do some actual coding. First I’ll present you the little trick inside the cell subclass.

class Cell: UICollectionViewCell {

    @IBOutlet weak var imageView: UIImageView!

    override var bounds: CGRect {
        didSet {
            layoutIfNeeded()
        }
    }

    override func awakeFromNib() {
        tremendous.awakeFromNib()

        imageView.layer.masksToBounds = true
    }

    override func layoutSubviews() {
        tremendous.layoutSubviews()

        setCircularImageView()
    }

    func setCircularImageView() {
        imageView.layer.cornerRadius = CGFloat(
            roundf(Float(imageView.body.dimension.width / 2.0))
        )
    }
}

Are you able to see it? Sure, you must override the bounds property. As the subsequent step now we have to put in writing the controller class with some fundamental knowledge supply for the gathering view and with the correct assist for the rotation strategies. 🤓

class ViewController: UICollectionViewController {

    override func collectionView(
        _ collectionView: UICollectionView,
        numberOfItemsInSection part: Int
    ) -> Int {
        30
    }

    override func collectionView(
        _ collectionView: UICollectionView,
        cellForItemAt indexPath: IndexPath
    ) -> UICollectionViewCell {

        let cell = collectionView.dequeueReusableCell(
            withReuseIdentifier: "Cell", 
            for: indexPath
        ) as! Cell

        cell.imageView.picture = UIImage(named: "Instance.jpg")
        cell.imageView.backgroundColor = .lightGray

        return cell
    }

    override func traitCollectionDidChange(
        _ previousTraitCollection: UITraitCollection?
    ) {
        tremendous.traitCollectionDidChange(previousTraitCollection)

        guard
            let previousTraitCollection = previousTraitCollection,
            traitCollection.verticalSizeClass != previousTraitCollection.verticalSizeClass ||
            traitCollection.horizontalSizeClass != previousTraitCollection.horizontalSizeClass
        else {
            return
        }

        collectionView?.collectionViewLayout.invalidateLayout()
        collectionView?.reloadData()
    }

    override func viewWillTransition(
        to dimension: CGSize, 
        with coordinator: UIViewControllerTransitionCoordinator
    ) {
        tremendous.viewWillTransition(to: dimension, with: coordinator)

        collectionView?.collectionViewLayout.invalidateLayout()

        coordinator.animate(alongsideTransition: { context in

        }, completion: { context in
            collectionView?.collectionViewLayout.invalidateLayout()

            collectionView?.visibleCells.forEach { cell in
                guard let cell = cell as? Cell else {
                    return
                }
                cell.setCircularImageView()
            }
        })
    }
}

extension ViewController: UICollectionViewDelegateFlowLayout {

    func collectionView(
        _ collectionView: UICollectionView,
        format collectionViewLayout: UICollectionViewLayout,
        sizeForItemAt indexPath: IndexPath
    ) -> CGSize {
        .init(
            width: collectionView.body.dimension.width/3.0 - 8,
            top: collectionView.body.dimension.width/3.0 - 8
        )
    }
}

If you’re accustomed to assortment views, you may ask why am I doing this tutorial? It’s so easy. It simply works, proper? No, really with out the overridden bounds property the instance would look one thing like this on the left aspect. 😢

Humorous, huh? The picture on the precise aspect is the precise outcome with the overridden bounds, that’s the anticipated conduct. Scrolling and rotation goes to be actually unusual should you don’t override bounds and also you don’t reset the cornerRadius property for the seen views. You may ask: however why? 🤔

Layers, springs & struts and a few clarification

Apple nonetheless has “Springs & Struts” primarily based code inside UIKit. Which means that body and certain calculations are occurring within the underlying system and the constraint system is attempting to work arduous as nicely to determine the correct measures.

“Springs & Struts” must die!

Whereas there may be an init(body:) methodology, or a required init(coder:) these format issues will suck as hell. I actually like Interface Builder, however till we can’t get a nice device to create nice person interfaces IB goes to be simply one other layer of potential bugs.

This subject received’t even be there should you create the cell from code solely utilizing auto format constraints or format anchors! It’s as a result of IB creates the cell primarily based on the body you gave in when you designed your prototype. However should you overlook init(body:) and also you simply create a brand new UIImageView occasion and let auto format do the arduous work, the format system will remedy all the pieces else. Verify this.

class Cell: UICollectionViewCell {

    weak var imageView: UIImageView!

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been carried out")
    }

    override init(body: CGRect) {
        tremendous.init(body: body)

        translatesAutoresizingMaskIntoConstraints = false

        let imageView = UIImageView()
        imageView.translatesAutoresizingMaskIntoConstraints = false
        addSubview(imageView)
        imageView = imageView

        imageView.topAnchor.constraint(equalTo: topAnchor)
        imageView.bottomAnchor.constraint(equalTo: bottomAnchor)
        imageView.leadingAnchor.constraint(equalTo: leadingAnchor)
        imageView.trailingAnchor.constraint(equalTo: trailingAnchor)
    }

    override func layoutSubviews() {
        tremendous.layoutSubviews()

        imageView.layer.masksToBounds = true
        imageView.layer.cornerRadius = CGFloat(
            roundf(Float(imageView.body.dimension.width/2.0))
        )
    }
}

Clearly it’s important to write extra code, register your cell class manually contained in the controller class and also you additionally should override the layoutSubviews methodology contained in the cell, but it surely’ll work as it’s anticipated. 🙄

collectionView?.register(Cell.self, forCellWithReuseIdentifier: "Cell")

Anyway, after you register the programmatically created cell you’ll have a pleasant approach of displaying round photographs. Utilizing this method is sort of difficult, but it surely undoubtedly works in each case. You may obtain the instance from The.Swift.Dev. tutorials on GitHub.