If a specific class implements a method (not it's superclasses).

gistfile1.m

BOOL KH_ClassImplementsSelector(Class aClass, SEL aSelector){
    Method          *methods;
    unsigned int    count;
    unsigned int    i;
	
    methods = class_copyMethodList(aClass, &count);
    BOOL implementsSelector = NO;
    for (i = 0; i < count; i++) {
        if (sel_isEqual(method_getName(methods[i]), aSelector)) {
            implementsSelector = YES;
            break;
        }
    }
    free(methods);
    return implementsSelector;
}