Customising Objective C

I have some obj-c code I want to integrate on all my builds into my main.mm 's main so that it executes when the app launches.

Its a tiny bit of obj-c, which I’d like to have
automatically added in when I do a unity build rather than hunting thru the xcode project copy pasting it back in each time I build.

whats the best way (I’m sure there must be one) to have these 6 lines of objc added in each time?

Edit the files in your .app container. Path is /Applications/Unity iPhone/Unity iPhone.app/Contents/Frameworks/iPhone-Trampoline

Excellent Thank you