Update README.md (#48)

Added ObjectivePGP to objective C section

README.md

@@ -277,8 +277,10 @@ encryption library providing MD5, SHA1, SHA2 hashing and HMAC functionality, as
 
 - [CocoaSecurity](https://github.com/kelp404/CocoaSecurity) - AES, MD5, SHA1, SHA224, SHA256, SHA384, SHA512, Base64, Hex.
 - [ObjC Themis](https://github.com/cossacklabs/themis/wiki/Objective-C-Howto) - ObjC wrapper on Themis for iOS and MacOS. High level crypto library for storing data (AES), secure messaging (ECC + ECDSA / RSA + PSS + PKCS#7) and session-oriented, forward secrecy data exchange (ECDH key agreement, ECC & AES encryption).
+- [ObjectivePGP](https://github.com/krzyzanowskim/ObjectivePGP) - ObjectivePGP is an implementation of OpenPGP protocol for iOS and macOS. OpenPGP is the most widely used email encryption standard.
 - [RNCryptor](https://github.com/RNCryptor/RNCryptor) - CCCryptor (AES encryption) wrappers for iOS and Mac.
 
+
 ### PHP
 
 - [halite](https://paragonie.com/project/halite) - Simple library for encryption using `libsodium`.