I could ask my watch to show me the last message or email I received through iMessage and it would pop up on the nano screen.

这样以来，我就能直接对着nano手表说话来让它在屏幕上显示刚收到的邮件和短信。

The sendMessage() function creates an AsyncMessage, which is an implementation of the IMessage interface, and then sends the message using the producer’s send() method.

sendMessage()函数先创建一个AsyncMessage，其是IMessage接口的一个实现，然后使用producer的send()方法发送此消息。