RNCryptor/Tests/RNCryptorTests/Data.swift

//
//  ByteArray.swift
//
//  Copyright © 2015 Rob Napier. All rights reserved.
//
//  This code is licensed under the MIT License:
//
//  Permission is hereby granted, free of charge, to any person obtaining a
//  copy of this software and associated documentation files (the "Software"),
//  to deal in the Software without restriction, including without limitation
//  the rights to use, copy, modify, merge, publish, distribute, sublicense,
//  and/or sell copies of the Software, and to permit persons to whom the
//  Software is furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
//  DEALINGS IN THE SOFTWARE.
//

import Foundation

internal extension String {
    var dataFromHexEncoding: Data? {
        let strip = [Character]([" ", "<", ">", "\n", "\t"])
        let input = characters.filter { c in !strip.contains(c)}

        guard input.count % 2 == 0 else { return nil }

        let data = NSMutableData()
        for i in stride(from: 0, to: input.count, by: 2) {
            guard var value = UInt8(String(input[i...i+1]), radix: 16) else { return nil }
            data.append(&value, length:1)
        }

        return data as Data
    }
}