apple-watch - iOS App 被杀，但 AppleWatch 可以向它发送消息？为什么？

Question

1. AppleWatch Enterforground，Watch 客户端发送字典 "@{@"check":@"I'm Back"}"
2. iOS 客户端收到 "@{@"check":@"I'm Back"} " ，使用静态 num i 重播字典为 "@{@"check":@"Rcheck_i"}"
3. 杀死 iOS 客户端
4. AppleWatch enterbackground, 5 second , enterforround , AppleWatch 从 ios 客户端收到消息为 "@{@"check":@"Rcheck_i"}"，怎么了？？？

谁能帮帮我，代码是...

//iOS客户端

static int i = 0;
- (void) session:(nonnull WCSession *)session didReceiveMessage:(nonnull NSDictionary<NSString *,id> *)message replyHandler:(nonnull void (^)(NSDictionary<NSString *,id> * __nonnull))replyHandler{
    dispatch_async(dispatch_get_main_queue(), ^{
        i++;
        NSString *temKey = [message.allKeys objectAtIndex:0];
        NSString *temStr = [NSString stringWithFormat:@"%@_%d",temKey,i];
        dispatch_async(dispatch_get_main_queue(), ^{
            self.statusLabel.text = temStr;
        });
        if([message objectForKey:@"check"]){
            NSString *temStr = [NSString stringWithFormat:@"Rcheck_%d",i];
            replyHandler(@{@"check":temStr});
        }
    });
}

//AppleWatch 客户端

static int i = 0;
- (void)willActivate {
    [super willActivate];
    i++;
    if ([WCSession isSupported] ) {
        WCSession* session = [WCSession defaultSession];
        session.delegate = self;
        [session activateSession];
        [self performSelector:@selector(checkAction) withObject:nil afterDelay:0.1];
    }
    else{
        [self.lblLockState setText:@"WATCH NOT support"];
    }
}

- (void) checkAction{
    WCSession* session = [WCSession defaultSession];
    [session sendMessage:@{@"check":@"I'm Back"} replyHandler:^(NSDictionary<NSString *,id> * _Nonnull replyHandler) {        
        dispatch_async(dispatch_get_main_queue(), ^{
            NSString *temStr;
            if ([replyHandler objectForKey:@"check"]) {
                temStr = [replyHandler objectForKey:@"check"] ;//[NSString stringWithFormat:@"CheckSucc_%d",i];
            }
            else{
                temStr = [NSString stringWithFormat:@"CheckSucc??_%d",i];
            }
            [self.lblLockState setText:temStr];
        });
    } errorHandler:^(NSError * _Nonnull error) {
        dispatch_async(dispatch_get_main_queue(), ^{
            NSString *temStr = [NSString stringWithFormat:@"CheckFail_%d",i];
            [self.lblLockState setText:temStr];
        });
    }];
}