title: How to replicate hash_hmac('sha256', $key, $secret_key) function in Swift 4?
body: <p>I've tried generating the hash_hmac('sha256', $key, $secret_key) php function equivalent in Swift 4 without success, after using libraries like CommonCrypto, CryptoSwift. I need these function for API authentication, using Alamofire library, which is a great library. Since i use Swift 4 the compatibility with other Swift libraries is not so good. Even with CryptoSwift which has the latest version(0.7.1) for Swift 4 i still get a lot of compatibility errors likes
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