UIMotionEffect Extensions

UIMotionEffectExtensions.swift

//
//  UIMotionEffectExtensions.swift
//  Collection Views
//
//  Created by jesse calkin on 3/30/16.
//  Copyright © 2016 Shoshin Boogie. All rights reserved.
//

import UIKit

extension UIMotionEffect {

    /**
     Creates a `UIInterpolatingMotionEffect` for both `x` and `y` axis.

     - parameter offset: `CGSize` for the amount of offset to be applied on the `x` and `y` axis when tilting the device.
     */
    class func tiltEffect(offset: CGSize) -> UIMotionEffect {
        let horizontalEffect = UIInterpolatingMotionEffect(keyPath: "center.x", type: UIInterpolatingMotionEffectType.TiltAlongHorizontalAxis)

        horizontalEffect.minimumRelativeValue = offset.width * -1
        horizontalEffect.maximumRelativeValue = offset.width

        let verticalEffect = UIInterpolatingMotionEffect(keyPath: "center.y", type: UIInterpolatingMotionEffectType.TiltAlongVerticalAxis)

        verticalEffect.minimumRelativeValue = offset.height * -1
        verticalEffect.maximumRelativeValue = offset.height

        let effectGroup = UIMotionEffectGroup()
        effectGroup.motionEffects = [horizontalEffect, verticalEffect]

        return effectGroup
    }
}