conath

import Foundation

extension Data {
    init?(hexString: String) {
        let len = hexString.count / 2
        var data = Data(capacity: len)
        for i in 0..<len {
            let j = hexString.index(hexString.startIndex, offsetBy: i*2)
            let k = hexString.index(j, offsetBy: 2)
            let bytes = hexString[j..<k]