ParallaxOverlay
ParallaxOverlay is a quick solution if you want parallax for your overlay view in UICollectionView.
Installation
SPM
ParallaxOverlay is available via Swift Package Manager.
Using Xcode 11, go to File -> Swift Packages -> Add Package Dependency and enter https://github.com/fortmarek/ParallaxOverlay
CocoaPods
ParallaxOverlay is available through CocoaPods. To install it, simply add the following line to your Podfile:
pod 'ParallaxOverlay'Implementing this is quite easy, firstly, use the provided custom UICollectionViewFlowLayout:
let parallaxLayout = ParallaxLayout()
let collectionView = UICollectionView(frame: .zero, collectionViewLayout: parallaxLayout)
// Our collection view needs to be bigger than our `view`, otherwise the cells would die when off-screen and our parallax values would just disappear
let collectionViewOverlap: CGFloat = 30
collectionView.contentInset = UIEdgeInsets(top: 0, left: -collectionViewOverlap, bottom: 0, right: collectionViewOverlap)
collectionView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: -collectionViewOverlap).isActive = true
collectionView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: collectionViewOverlap).isActive = trueThen go to your UICollectionViewCell that you use in the UICollectionView which you just created and let's implement func apply(_ layoutAttributes: UICollectionViewLayoutAttributes) function where we need to specify how to actually apply our parallax:
// Applying parallaxValue
override func apply(_ layoutAttributes: UICollectionViewLayoutAttributes) {
super.apply(layoutAttributes)
guard let layoutAttributes = layoutAttributes as? ParallaxLayoutAttributes else { return }
// Max horizontal parallax from initial position
let maxHorizontalParallax: CGFloat = 80
// Default leading offset of infoStackView
yourParallaxConstraint.constant = layoutAttributes.parallaxValue * maxHorizontalParallax
}In this function we just apply parallaxValue to the constraint we would like to move off the axis.
...and we are all set!