Create SAS Token In Swift

    func createSharedAccessToken(uri: String, saName: String, saKey: String) -> String {
        let uriEncoded = uri.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed)!
        let date = Date()
        let calendar = Calendar.current
        let exp = calendar.date(byAdding: .minute, value: 60, to: date)!
        let ttl = UInt64(floor((exp.timeIntervalSince1970)))
        let signature = "\(uriEncoded)\n\(ttl)"
        let signatureData = signature.data(using: .utf8)!
        let keyData = saKey.data(using: .utf8)!
        let hash = self.hmacSHA256(message: signatureData, key: keyData)
        let hashString = String(data: hash, encoding: .utf8)!

        return "SharedAccessSignature sr=\(uriEncoded)&sig=\(hashString)&se=\(ttl)&skn=\(saName)"
    }

    private func hmacSHA256(message: Data, key: Data) -> Data {
        var macData = Data(count: Int(CC_SHA256_DIGEST_LENGTH))

        macData.withUnsafeMutableBytes {macBytes in
            message.withUnsafeBytes {messageBytes in
                key.withUnsafeBytes {keyBytes in
                    CCHmac(CCHmacAlgorithm(kCCHmacAlgSHA256),
                           keyBytes, key.count,
                           messageBytes, message.count,
                           macBytes)
                }
            }
        }
        return macData
    }