Thin wrapper for UIView.animateKeyframes

KeyframeAnimator.swift

import UIKit

final class KeyframeAnimator {

    private struct AnimationsData {
        let animations: Animations
        let relativeTimeStart: Double
        let relativeDuration: Double
    }

    typealias Animations = () -> Void

    private var animationsDataList = [AnimationsData]()

    func addKeyframe(withRelativeStartTime relativeStartTime: Double, relativeDuration: Double, animations: @escaping Animations) -> KeyframeAnimator {
        let data = AnimationsData(
            animations: animations,
            relativeTimeStart: relativeStartTime,
            relativeDuration: relativeDuration
        )

        animationsDataList.append(data)

        return self
    }

    func animate(withDuration duration: TimeInterval, delay: TimeInterval = 0.0, options: UIViewKeyframeAnimationOptions = [], completion: ((Bool) -> Void)? = nil) {
        UIView.animateKeyframes(
            withDuration: duration,
            delay: delay,
            options: options,
            animations: { [animationsDataList] in
                for data in animationsDataList {
                    UIView.addKeyframe(
                        withRelativeStartTime: data.relativeTimeStart,
                        relativeDuration: data.relativeDuration,
                        animations: data.animations
                    )
                }
            },
            completion: completion
        )

        animationsDataList = []
    }
}

extension UIView {

    static var keyframeAnimator: KeyframeAnimator {
        return KeyframeAnimator()
    }
}