How to reduce code size of iPhone app?

Question

My iPhone app is getting ready to go to production and we like to cram in as much data as possible. When I poke around the generated .app file for my application I see a file named <executable name> which I assume is the compiled code. It is about 2.5 megs which seem large for what I am including in my app. What type of things should I check to make sure there aren't any unneeded items being included into my executable?

Answer 1

There are a number of things you could do -- 2.5 MB is a small app.

• One obvious way is to verify that your binary is in fact stripped. This removes unused references (e.g. functions which are not actually called) and debugging info.

• Link Time Optimization (LTO) can save you a ton of space, although that applies to the C and C++ aspects of your program. It brought one of my programs down to about 1/5 the size.

• Play with optimization settings. O3 and O2 often produce a smaller binary than Os.

• Keep track of your dependent libraries. Their exported symbols may be relatively large.

• Favor C or C++ for shared libraries in larger projects. If unused, they may be stripped or optimized away.

• Minimize static data and static functions, restricting their scope to the c, cpp, m, mm file.