This is an older cocoa/objective C project. It's goal was to offer an easy to use crypto app (ecnryption/decryption of files), which included numerous implementations of ciphers, via plug-in functionality. AES128 and RC4 should be functional. A sample ROT128 plug-in is included. It is not being maintained anymore, so use at your own risk. The code might be quite outdated. But if you find the code useful, please use it. It's licenced under GPL3.
nylki/kryptomator
Older cocoa/objective C project to offer intuitive encryption/decryption with cipher plugin
Objective-C