UIColor from hex code - Swift

UIColor from Hex Swift

convenience init(rgba: String) {
    var red:   CGFloat = 0.0
    var green: CGFloat = 0.0
    var blue:  CGFloat = 0.0
    var alpha: CGFloat = 1.0
    
    let formattedCode = rgba.stringByReplacingOccurrencesOfString("#", withString: "")
    let formattedCodeLength = count(formattedCode)
    if formattedCodeLength != 3 && formattedCodeLength != 4 && formattedCodeLength != 6 && formattedCodeLength != 8 {
        fatalError("invalid color")
    }
    
    var hexValue: UInt32 = 0
    if NSScanner(string: formattedCode).scanHexInt(&hexValue) {
        switch formattedCodeLength {
        case 3:
            red   = CGFloat((hexValue & 0xF00) >> 8)       / 15.0
            green = CGFloat((hexValue & 0x0F0) >> 4)       / 15.0
            blue  = CGFloat(hexValue & 0x00F)              / 15.0
        case 4:
            red   = CGFloat((hexValue & 0xF000) >> 12)     / 15.0
            green = CGFloat((hexValue & 0x0F00) >> 8)      / 15.0
            blue  = CGFloat((hexValue & 0x00F0) >> 4)      / 15.0
            alpha = CGFloat(hexValue & 0x000F)             / 15.0
        case 6:
            red   = CGFloat((hexValue & 0xFF0000) >> 16)   / 255.0
            green = CGFloat((hexValue & 0x00FF00) >> 8)    / 255.0
            blue  = CGFloat(hexValue & 0x0000FF)           / 255.0
        case 8:
            red   = CGFloat((hexValue & 0xFF000000) >> 24) / 255.0
            green = CGFloat((hexValue & 0x00FF0000) >> 16) / 255.0
            blue  = CGFloat((hexValue & 0x0000FF00) >> 8)  / 255.0
            alpha = CGFloat(hexValue & 0x000000FF)         / 255.0
        default:
            print("Invalid RGB string, number of characters after '#' should be either 3, 4, 6 or 8")
        }
    }
    self.init(red:red, green:green, blue:blue, alpha:alpha)
}