Hi,
Code Blocks supports only syntax highlighting for C,C++ but not for Objective-C and Objective-C++.
Gcc and clang both support Objective-C.
Adding file associations(*.m,*.mm) and syntax highlighting (keywords: @interface @implementation @protocol @end @private @protected @public @try @throw @catch @finally.@class @selector @encode @synchronized @property @package @required @optional @synthesize and @dynamic in out inout bycopy byref onewaq YES NO self id ) should be easy.
An objective-c compiler should not be bundled yet with code blocks mingw until llvm is used for code completion.