A few days of hard done nights were all inspired by faulty encodings. Talk about "Hello World" experiences LOL. Keeping things in mind, to really smooth things up between Objective-C and PHP, in any Objective-C functions needing to encode/decode strings like PHP, here's the encoding type:
Do not interchange this with any other or things will go wrong :( Here are snippets to generate HMAC-SHA1 hashes in its Base64 form encoded correctly for OAUTH v1.0a authentication.
The Base64Transcoder library is the work of Jonathan Wright, available at http://code.google.com/p/oauth/. Cheers!