Objective-C Category Causing unrecognized selector

A couple possibilities:

1. You did not link UIImage+TTShare.m into your target. So while you have the header, you're not compiling the implementation.
2. If this is part of a static library, you need to add -all_load to the Other Linker Flags build setting for the app linking against the library.

If you want to use Category method, you must add -ObjC to the Other Linker Flags build setting of your APP.

I had the same issue and had to apply this fix as well. My NSDate-Extensions.m source file wasn't compiling so I had to go into Project Settings, then select the appropriate target, then click the "Build Phases" tab, then expand the "Compile Sources" items, then click the + symbol and manually add my NSDate-Extensions.m file.