One obstacle that I faced long time ago and came again into spotlight is how to recompile GDB for iOS. It is not useful to fix the ARM disassembler and then not be able to compile. As far as I know there isn’t any documentation available or an easy method to accomplish this – Saurik’s build environment is not public (?) and Apple sources do not compile directly. Darwinbuild project works great for OS X but it’s a question mark for iOS....
MacHeist released a great puzzle game called The Heist, promising a prize when you managed to open the safe. Since I am a sucker for puzzle games I bought it and gave a brief check on its code. There is a single url in the program and some references to SHA256, this being a good indicator that they thought a little about security. I started playing the game and finally opened the safe....
I just finished porting gdbinit to iOS. The basic stuff is working except the stepo command (one of my favourites!), the Objective-C selector and showing what will happen with conditional branches (I have to see how to implement this since ARM instructions can be conditional). I have tested it on my iPad with GDB available from Cydia (it seems you can use Apple’s version) and it works, so it should give no special problems with other iOS devices....