How to create a parallax effect in UIKit

Swift version: 5.2

Paul Hudson @twostraws May 28th 2019

Parallax effects have been standard since iOS 7.0, and the UIInterpolatingMotionEffect class makes this easy by automatically smoothing accelerometer input so your views can adjust to tilt data.

If you want to have a UIView respond to tilting, add this function to your code then call it on any view you want:

func addParallaxToView(vw: UIView) {
    let amount = 100

    let horizontal = UIInterpolatingMotionEffect(keyPath: "center.x", type: .tiltAlongHorizontalAxis)
    horizontal.minimumRelativeValue = -amount
    horizontal.maximumRelativeValue = amount

    let vertical = UIInterpolatingMotionEffect(keyPath: "center.y", type: .tiltAlongVerticalAxis)
    vertical.minimumRelativeValue = -amount
    vertical.maximumRelativeValue = amount

    let group = UIMotionEffectGroup()
    group.motionEffects = [horizontal, vertical]
    vw.addMotionEffect(group)
}