来自服务器的 iOS tcp 套接字 json

Question

在我的应用程序中，我打开一个到我的服务器的 TCP 套接字连接，然后等待数据。我的服务器以 JSON 格式发送所有数据，从服务器发送的消息可能如下所示:

{\"type\":\"message\", \"msg\": \"\", \"visitorNick\": \"nickName\", \"customField1\": \"\", \"visitorNick\": \"Visitor " + obj.channel + "\", \"time\": \"" + getDateTime() + "\", \"channel\": \"" + obj.channel + "\"}\n

在我的应用程序中，我正在使用运行循环来阅读:

- (void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent {


    switch (streamEvent) {

        case NSStreamEventOpenCompleted:
            NSLog(@"Stream opened");

            break;
        case NSStreamEventHasBytesAvailable:



            if (theStream == inputStream) {


                uint8_t buffer[1024];
                int len;
                NSMutableData *output = [[NSMutableData alloc] initWithLength:0];
                while ([inputStream hasBytesAvailable]) {
                    len = [inputStream read:buffer maxLength:sizeof(buffer)];
                    if (len > 0) {
                        [output appendBytes: (const void *)buffer length:len];
                    }
                }

                NSString *outputData = [[NSString alloc] initWithData:output encoding:NSUTF8StringEncoding];

                outputData = [outputData stringByReplacingOccurrencesOfString:@"\n" withString:@" "];
                outputData = [outputData stringByReplacingOccurrencesOfString:@"} {"
                                                     withString:@"} , {"];



                NSLog(@"RECIEVED ----------------------> %@", outputData);

                // Parse the message and add it to the right method
                NSError* error;
                NSDictionary *JSON =
                [NSJSONSerialization JSONObjectWithData: [outputData dataUsingEncoding:NSUTF8StringEncoding]
                                                options: NSJSONReadingMutableContainers
                                                  error: &error];


                NSString* type = [JSON objectForKey:@"type"];

                if(error) {
                    NSLog(@"PARSE ERROR ------------->>>>> : %@\n", error);
                }

                NSLog(@"SERVER TYPE --> %@\n", type);

                if([type isEqualToString:@"message"]) {
                    //NSLog(@"New chat message: %@", output);

                    [self messageReceived:outputData];

                }

            }
            break;


        case NSStreamEventErrorOccurred:

            NSLog(@"Can not connect to the host!");
            isConnected = 0;

            [[NSNotificationCenter defaultCenter] postNotificationName:@"showReconnect" object:nil];
            [NSThread sleepForTimeInterval:3.06];
            [self initNetworkCommunication];

            break;

        case NSStreamEventEndEncountered:

            [theStream close];
            [theStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
            NSLog(@"STREAM PAUSED");
            theStream = nil;

            break;

    }
}

我希望 \n 强制应用程序一次读取一个 JSON(例如，在 java 中，\n 用作刷新，因此一条消息一次读取)。现在，该应用有时会一次读取多个 JSON。

我认为问题出在这里:

            uint8_t buffer[1024];
            int len;
            NSMutableData *output = [[NSMutableData alloc] initWithLength:0];
            while ([inputStream hasBytesAvailable]) {
                len = [inputStream read:buffer maxLength:sizeof(buffer)];
                if (len > 0) {
                    [output appendBytes: (const void *)buffer length:len];
                }
            }

但我不确定如何强制应用一次只从服务器读取一个 JSON。

有什么想法吗？

Answer 1

如果每个 JSON block 在一行上发送，并且各行之间用换行符分隔字符，您可以执行以下操作:

• 将属性(或实例变量)NSMutableData *collectedData 添加到您的类中。

• 在情况下 NSStreamEventOpenCompleted: 初始化收集的数据:

  collectedData = [NSMutableData data];
  

• 在 case NSStreamEventHasBytesAvailable: 中，将所有接收到的数据附加到收集的数据。然后检查是否有换行符。在这种情况下，提取行(从开始到换行符)到一个单独的 NSData 对象并将其从收集的数据中删除。这可能类似于以下(未经测试的)代码:

  NSData *nl = [@"\n" dataUsingEncoding:NSUTF8StringEncoding];
  
  uint8_t buffer[1024];
  int len;
  while ([inputStream hasBytesAvailable]) {
      len = [inputStream read:buffer maxLength:sizeof(buffer)];
      [collectedData appendBytes: (const void *)buffer length:len];
  }
  NSRange nlRange =[collectedData rangeOfData:nl options:0 range:NSMakeRange(0, [collectedData length])];
  while (nlRange.location != NSNotFound) {
      // Extract data from the beginning up to (but not including) the newline character:
      NSData *jsonData = [collectedData subdataWithRange:NSMakeRange(0, nlRange.location)];
      // Remove data from the beginning up to and including the newline character:
      [collectedData replaceBytesInRange:NSMakeRange(0, nlRange.location + nlRange.length) withBytes:NULL length:0];
  
      // Process jsonData ...
      NSError *error;
      NSMutableDictionary *jsonDict = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:&error];
      // ...
  
      // Check for another newline character:
      nlRange =[collectedData rangeOfData:nl options:0 range:NSMakeRange(0, [collectedData length])];
  }