SKTexture gradient extension

SKTexture gradient extension

//
//  Extensions.swift
//  WordSnatch
//
//  Created by Craig on 24/03/2015.
//  Copyright (c) 2015 Interactive Coconut. All rights reserved.
//

import SpriteKit
import UIKit

//inspired by https://gist.github.com/Tantas/7fc01803d6b559da48d6
enum GradientDirection {
    case up
    case left
    case upLeft
    case upRight
}
extension SKTexture {
    
    convenience init(size:CGSize,color1:CIColor,color2:CIColor,direction:GradientDirection = .up) {
        let coreImageContext = CIContext(options: nil)
        let gradientFilter = CIFilter(name: "CILinearGradient")
        gradientFilter.setDefaults()
        var startVector:CIVector
        var endVector:CIVector
        switch direction {
        case .up:
            startVector = CIVector(x: size.width/2, y: 0)
            endVector = CIVector(x: size.width/2, y: size.height)
        case .left:
            startVector = CIVector(x: size.width, y: size.height/2)
            endVector = CIVector(x: 0, y: size.height/2)
        case .upLeft:
            startVector = CIVector(x: size.width, y: 0)
            endVector = CIVector(x: 0, y: size.height)
        case .upRight:
            startVector = CIVector(x: 0, y: 0)
            endVector = CIVector(x: size.width, y: size.height)
            
        }
        gradientFilter.setValue(startVector, forKey: "inputPoint0")
        gradientFilter.setValue(endVector, forKey: "inputPoint1")
        gradientFilter.setValue(color1, forKey: "inputColor0")
        gradientFilter.setValue(color2, forKey: "inputColor1")
        let cgimg = coreImageContext.createCGImage(gradientFilter.outputImage, fromRect: CGRect(x: 0, y: 0, width: size.width, height: size.height))
        self.init(CGImage:cgimg)
    }
}

extension UIColor {
    //credit: http://stackoverflow.com/a/29218836/3220708
    convenience init(var hex: String) {
        var alpha: Float = 100
        let hexLength = countElements(hex)
        if !(hexLength == 7 || hexLength == 9) {
            // A hex must be either 7 or 9 characters (#GGRRBBAA)
            println("improper call to 'colorFromHex', hex length must be 7 or 9 chars (#GGRRBBAA)")
            self.init(white: 0, alpha: 1)
            return
        }
        
        if hexLength == 9 {
            var temp = hex[7...8]
            alpha = temp.floatValue
            hex = hex[0...6]
        }
        
        // Establishing the rgb color
        var rgb: UInt32 = 0
        var s: NSScanner = NSScanner(string: hex)
        // Setting the scan location to ignore the leading `#`
        s.scanLocation = 1
        // Scanning the int into the rgb colors
        s.scanHexInt(&rgb)
        
        // Creating the UIColor from hex int
        self.init(
            red: CGFloat((rgb & 0xFF0000) >> 16) / 255.0,
            green: CGFloat((rgb & 0x00FF00) >> 8) / 255.0,
            blue: CGFloat(rgb & 0x0000FF) / 255.0,
            alpha: CGFloat(alpha / 100)
        )
    }
}


extension String {

    //credit: http://stackoverflow.com/questions/24092884/get-nth-character-of-a-string-in-swift-programming-language/24144365#24144365
    subscript (r: Range<Int>) -> String {
        get {
            let startIndex = advance(self.startIndex, r.startIndex)
            let endIndex = advance(startIndex, r.endIndex - r.startIndex)
            
            return self[Range(start: startIndex, end: endIndex)]
        }
    }
    //credit: http://stackoverflow.com/questions/24085665/convert-string-to-float-in-apples-swift/24088249#24088249
    var floatValue: Float {
        return (self as NSString).floatValue
    }
}

Compatibility for Swift 2 with Doc Blocks: https://gist.github.com/RayHughes/3162fcbda6439893b539