WWDC23 SALE: Save 50% on all my Swift books and bundles! >>

How to create keyframe animations using CAKeyframeAnimation

Swift version: 5.6

Paul Hudson    @twostraws   

Keyframe animations offer extraordinary power for developers because they let you set multiple values and have iOS animate between them over times you specify. There are three components: a key path (the property to animate), an array of values (the value you want to use for that property), and an array of key times (when that value should be used for the property).

The number of key times needs to match the number of values, because each value is applied in order when its key time is reached. In the example code below, a view will be moved down 300 points then back to its starting point over 2 seconds. It's important that you understand the key times and duration are separate: the key times should be between 0 and 1, where 0 means "the start of the animation" and 1 means "the end of the animation."

let animation = CAKeyframeAnimation()
animation.keyPath = "position.y"
animation.values = [0, 300, 0]
animation.keyTimes = [0, 0.5, 1]
animation.duration = 2
animation.isAdditive = true

vw.layer.add(animation, forKey: "move")

Because the animation is marked as additive, it means that 300 is relative to its starting position.

We can use key frame animations to create a simple shake effect that moves a view left and right across a brief animation. This will use additive animations again because we want to specify relative values (move to the left and right a bit) rather than absolute values:

func shakeView(vw: UIView) {
    let animation = CAKeyframeAnimation()
    animation.keyPath = "position.x"
    animation.values = [0, 10, -10, 10, -5, 5, -5, 0 ]
    animation.keyTimes = [0, 0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875, 1]
    animation.duration = 0.4
    animation.isAdditive = true

    vw.layer.add(animation, forKey: "shake")
}
Save 50% in my WWDC23 sale.

SAVE 50% To celebrate WWDC23, all our books and bundles are half price, so you can take your Swift knowledge further without spending big! Get the Swift Power Pack to build your iOS career faster, get the Swift Platform Pack to builds apps for macOS, watchOS, and beyond, or get the Swift Plus Pack to learn advanced design patterns, testing skills, and more.

Save 50% on all our books and bundles!

Available from iOS 2.0

Similar solutions…

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.

BUY OUR BOOKS
Buy Pro Swift Buy Pro SwiftUI Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let us know!

Average rating: 4.8/5

 
Unknown user

You are not logged in

Log in or create account
 

Link copied to your pasteboard.