I\'m developing an iOS application that needs to deploy to iOS 3.1.3. I need to extend some of the functionality of the NSData class and am using the following code inside N
It really seems like your category isn't being compiled or linked into the same target that you're using it from. You should make sure that NSData+Base64.m is marked to be compiled by the same target that it's being used from by getting info on the two files and comparing the targets they're assigned to.
A test you can perform is to add a line with an #error error message to NSData+Base64.m, which will cause the build to fail when it gets to that file. Like this:
#error We're now compiling NSData+Base64.m
Then look and see which target fails to compile.