实例方法的消息转发

- (int)sheep:(int)time;

#pragma mark 实例方法的消息转发
+ (BOOL)resolveInstanceMethod:(SEL)sel {
    if (sel == @selector(sheep:)) {
        NSLog(@"+ resolveInstanceMethod");
        return YES;
    }
    return [super resolveInstanceMethod:sel];
}
- (id)forwardingTargetForSelector:(SEL)aSelector {
    if (aSelector == @selector(sheep:)) {
        NSLog(@"- forwardingTargetForSelector");
        return nil;
    }
    return [super forwardingTargetForSelector:aSelector];
}
- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector {
    if (aSelector == @selector(sheep:)) {
        NSLog(@"- methodSignatureForSelector");
        return [NSMethodSignature signatureWithObjCTypes:"i@:i"];
    }
    return [super methodSignatureForSelector:aSelector];
}
- (void)forwardInvocation:(NSInvocation *)anInvocation {
    if (anInvocation.selector == @selector(sheep:)) {
        NSLog(@"- forwardInvocation");
        int retValue;
        [anInvocation getReturnValue:&retValue];
        int time;
        [anInvocation getArgument:&time atIndex:2];
        NSLog(@"retValue %d", retValue);
        NSLog(@"time %d", time);
    }
}