ColorWithHex.swift

  convenience init(hexString: String) {
    let hexString = hexString.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
    let scanner = NSScanner(string: hexString)

    if (hexString.hasPrefix("#")) {
      scanner.scanLocation = 1
    }

    var color: UInt32 = 0
    scanner.scanHexInt(&color)

    let mask = 0x000000FF
    let r = Int(color >> 16) & mask
    let g = Int(color >> 8) & mask
    let b = Int(color) & mask

    let red   = CGFloat(r) / 255.0
    let green = CGFloat(g) / 255.0
    let blue  = CGFloat(b) / 255.0

    self.init(red:red, green:green, blue:blue, alpha:1)
  }