CIColorExtension.swift 'characters' is deprecated: Please use String or Substring directly

[carlosguedes]

Dear Alexander, how are you?

On swift 4 build IOS 11 I'm facing a warning that is relatively easy to solve:

Class: CIColorExtension.swift
Line 32:

if scanner.scanHexInt64(&hexValue) {
let length = rgba.characters.count

Warning Message: 'characters' is deprecated: Please use String or Substring directly

Thanks

[karthisiva]

use
let length = rgba.count