dynamicMethod

gistfile1.m

void dynamicMethodIMP(id self, SEL _cmd)
{
    // implementation ....
}

//该方法在OC消息转发生效前被调用
+ (BOOL) resolveInstanceMethod:(SEL)aSEL
{
    if (aSEL == @selector(resolveThisMethodDynamically))
    {
          //向[self class]中新加入返回为void的实现，SEL名字为aSEL，实现的具体内容为dynamicMethodIMP
          class_addMethod([self class], aSEL, (IMP) dynamicMethodIMP, "v@:");
          return YES;
    }
    return [super resolveInstanceMethod:aSel];
}