iOS 消息转送 与 消息禁用

消息转送

• 重写respondsToSelector

- (BOOL)respondsToSelector:(SEL)aSelector {
    if ([super respondsToSelector:aSelector]) {
        return YES;
    } else if ([self methodForSelector:aSelector] != (IMP)NULL) {
        return YES;
    } else {
        return [self.someObj respondsToSelector:aSelector];
    }
    return NO;
}

- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector {
    if ([super respondsToSelector:aSelector]) {
        return [super methodSignatureForSelector:aSelector];
    }
    return [self.someObj methodSignatureForSelector:aSelector];
}

- (void)forwardInvocation:(NSInvocation *)anInvocation {
    SEL selector = [anInvocation selector];
    if ([self.someObj respondsToSelector:selector]) {
        [anInvocation invokeWithTarget:self.third];
    } else {
        [super forwardInvocation:anInvocation];
    }
}

消息禁用

- (void)setSize:(NSSize *)size {
    [self doesNotRecognizeSelector:_cmd];
}