After [decrypting an IPA file on a jailbroken iDevice][1], you can use a much more affordable alternative to IDA Pro called **Hopper** - the multi-platform disassembler for < $100.

https://www.hopperapp.com/

It has support for analyzing iOS executables (among others) and even comes with the ability to convert ARM assembly to pseudo-C.

![Hopper screenshot with example disassembly and pseudocode][3]


  [1]: https://github.com/stefanesser/dumpdecrypted
  [3]: https://i.sstatic.net/GfUK2.jpg