基于iOS socket的聊天，如何接收app在后台发送的消息?

For fun I've built a little socket based chat application. It is speaking over tcp socket with a nodejs server. Its successfully sending messages back and forth. However, the problem occurs when i press the home button and put my app in the background - at this point the socket seems to be "paused" and all messages that are sent during this time are lost.For fun I've built a little socket based chat a