Decompiling iOS Objective-C binaries [duplicate]

Answer 1

As noted here, you can get the assembly code, but you'll never be able to get the source code since there are an indefinite number of ways to represent the assembly.

Answer 2

The binary of all apps from the iOS App store, and on the filesystems of stock OS devices, is encrypted.

Try writing the authors of the app very politely, and see if they'll give or offer to sell you source code for the parser in which you're interested.