I found a bug today with Xcode’s refactoring tool (radar://5723465) that could be a headache if you don’t watch for it. If you refactor the name of a method, calls to used through an @selector, like [self performSelectorOnMainThread:@selector(someMethod:) withObject:obj waitUntilDone:NO], will not be changed. You have to pick those up yourself. This could be a headache since it won’t be caught until runtime.