CurvedKeyframeAnimationOptions.swift

public extension UIViewKeyframeAnimationOptions {
    // This exists because keyframe options doesn't expose the easing for the overall curve
    public init(keyframeAnimationsOptions: UIViewKeyframeAnimationOptions, animationCurve: UIViewAnimationCurve) {
        let animationOptions: UIViewAnimationOptions
        switch animationCurve {
        case .EaseIn: animationOptions = .CurveEaseIn
        case .EaseInOut: animationOptions = .CurveEaseInOut
        case .EaseOut: animationOptions = .CurveEaseOut
        case .Linear: animationOptions = .CurveLinear
        }
        self = UIViewKeyframeAnimationOptions(rawValue: keyframeAnimationsOptions.rawValue | animationOptions.rawValue)
    }
}