A drop-in replacement for CABasicAnimation that offers more flexible tweening.
To see it in action, simply run the included iOS app -- it should work fine in the simulator or on a physical device.
To use in your own code, simply copy TweenAnimation.swift into your project. Once that's done, you can use TweenAnimation much like you would CABasicAnimation (docs):
let animation = TweenAnimation(keyPath: "translation.y")
animation.fromValue = 0.0
animation.toValue = 10.0
animation.duration = 1.0
(...)...but instead of setting timingFunction to control the way your values are interpolated, you set tweenFunction. You can use a predefined tween / ease function like sinEaseInOut:
(...)
animation.tweenFunction = TweenAnimation.sinEaseInOut
myScnNode.addAnimation(animation, forKey: "myAnimation")...or a custom tween function of your own devising:
(...)
animation.tweenFunction = {
return $0 * ($0 + 0.02) * (50.0/51.0)
}
myScnNode.addAnimation(animation, forKey: "myAnimation")If you provide a custom tween function, the input it receives will be a normalized time value (ie. from 0.0 to 1.0), and the output it provides (typically also from 0.0 to 1.0, but not necessarily) will be used, at the given time, as a multiplier for the difference between the initial and final values.
Internally, TweenAnimation uses the typealias TweenFloat for its floating-point calculations. You can rebind that typealias to Double, Float or CGFloat to reflect whichever native data type you'll be working with most in your code, to minimize the amount of explicit casting / type conversion necessary.
Note that while CABasicAnimation doesn't actually require you to set any from/by/to values, TweenAnimation will only work if at least two of fromValue, byValue, and toValue are set (if all three are set, byValue is ignored).
The demo project uses Xcode 9 and Swift 4, but the code will also work as-is with Swift 3; it doesn't use any Swift-4-specific syntax or language features.
(These can all be visually demonstrated and compared by running the included test app.)
.linearEase.sinEase/.sineEaseIn/.sineEaseOut/.sineEaseInOut.power2EaseIn/.power2EaseOut/.power2EaseInOut(quadratic).power3EaseIn/.power3EaseOut/.power3EaseInOut(cubic).power4EaseIn/.power4EaseOut/.power4EaseInOut(quartic).power5EaseIn/.power5EaseOut/.power5EaseInOut(quintic).expoEaseIn/.expoEaseOut/.expoEaseInOut(exponential).circEaseIn/.circEaseOut/.circEaseInOut(circular).bounceEaseIn/.bounceEaseOut/.bounceEaseInOut.backEaseIn/.backEaseOut/.backEaseInOut.elasticEaseIn/.elasticEaseOut/.elasticEaseInOut
(These can all be visually demonstrated and compared by running the included test app.)
animateFade()/animateFadeIn()/animateFadeOut()animatePulse()/animatePulseUpward()animateSquashAndStretch()animateHop()/animateSquashHop()animateBob()animateHonk()