Get UIColor from hex value

UIColor+Hex.swift

// MARK: - HEX init
// From Tim Shadel

enum UIColorInputError: ErrorType {
    case UnableToScanHexValue
}

extension UIColor {
    
    convenience init(hex: Int, alpha: CGFloat = 1.0) {
        let red = CGFloat((hex >> 16) & 0xFF)/255.0
        let green = CGFloat((hex >> 8) & 0xFF)/255.0
        let blue = CGFloat((hex) & 0xFF)/255.0
        
        self.init(red: red, green: green, blue: blue, alpha: alpha)
    }

    convenience init(hexString: String, alpha: CGFloat = 1.0) throws {
        var hexValue: UInt32 = 0
        guard NSScanner(string: hexString).scanHexInt(&hexValue) else { throw UIColorInputError.UnableToScanHexValue }
        self.init(hex: Int(hexValue), alpha: alpha)
    }
    
    var hexString: String {
        var red: CGFloat = 0, green: CGFloat = 0, blue: CGFloat = 0, alpha: CGFloat = 0
        if !self.getRed(&red, green: &green, blue: &blue, alpha: &alpha) {
            self.getWhite(&red, alpha: &alpha)
            green = red
            blue = red
        }
        
        red = CGFloat(roundf(Float(red) * 255.0))
        green = CGFloat(roundf(Float(green) * 255.0))
        blue = CGFloat(roundf(Float(blue) * 255.0))
        alpha = CGFloat(roundf(Float(alpha) * 255.0))
        
        // Ignore alpha for now
        let hex: UInt = (UInt(red) << 16) | (UInt(green) << 8) | (UInt(blue))
        return String(format: "%06x", hex)
    }
    
}


extension UIColor: ValueType {
    public static func value(object: Any) throws -> UIColor {
        guard let colorString = object as? String, objectValue = try? UIColor(hexString: colorString) else {
            throw Error.TypeMismatch(expected: self, actual: object.dynamicType)
        }
        return objectValue
    }
}