Now that those methods are defined (TWRobot+Drawing.h) and implemented (TWRobot+Drawing.m) I'd like to use them in the core class (TWRobot.m). This works, I just get a lot of compiler warnings. All the warnings are in the form: `TWRobot' may not respond to `<method defined in TWRobot+Drawing.h>' cannot find method `<method defined in TWRobot+Drawing.h>'; return type of `id' assumed So like I said, everything works: when I call the methods they're executed as they should be, I've just got these ugly warnings all over the place. Am I doing something wrong or will I just have to live with it?