SKTexture Gradient

SKTexture+Gradient.swift

extension SKTexture {
    /* FIXME
        This code breaks on iOS 8 (reference post)
        http://stackoverflow.com/questions/19243111/spritekit-sktexture-crash/19248293#19248293
    */

    convenience init(size: CGSize, firstColor: UIColor, lastColor: UIColor) {

        guard let gradientFilter = CIFilter(name: "CILinearGradient") else {
            self.init()
            return
        }

        gradientFilter.setDefaults()

        let startVector = CIVector(x: size.width/2.0, y: 0)
        let endVector = CIVector(x: size.width/2.0, y: size.height)
        gradientFilter.setValue(startVector, forKey: "inputPoint0")
        gradientFilter.setValue(endVector, forKey: "inputPoint1")

        let transformedFirstColor = CIColor(color: firstColor)
        let transformedLastColor = CIColor(color: lastColor)
        gradientFilter.setValue(transformedFirstColor, forKey: "inputColor1")
        gradientFilter.setValue(transformedLastColor, forKey: "inputColor0")

        guard let outputImage = gradientFilter.outputImage else {
            self.init()
            return
        }

        let context = CIContext()
        let image = context.createCGImage(outputImage, fromRect: CGRect(x: 0, y: 0, width: size.width, height: size.height))
        
        self.init(CGImage: image)
    }
}