Creating a skew in SpriteKit

skew.swift

// https://stackoverflow.com/a/43532815/1492368

extension SKSpriteNode {

    func addSkew(value: CGFloat = -1){

        var effectNode = SKEffectNode()
        effectNode.shouldRasterize = true
        effectNode.shouldEnableEffects = true
        effectNode.addChild(SKSpriteNode(texture: texture))
        effectNode.zPosition = 1
        let transform = CGAffineTransform(a:  1    , b:  0,
                                          c:  value, d:  1,
                                          tx: 0    , ty: 0)
        let transformFilter = CIFilter(name: "CIAffineTransform")!
        transformFilter.setValue(transform, forKey: "inputTransform")
        effectNode.filter = transformFilter
        addChild(effectNode)
        texture = nil

    }

}