苹果开发者文档这样介绍XPC：
解释：
Access a low-level (libSystem) interprocess communication mechanism that is based on serialized property lists. (访问基于序列化属性列表的低级（libSystem）进程间通信机制。)
总览：
The XPC Services API provides a low-level (libSystem) interprocess communication mechanism based on serialized property lists.（XPC Services API提供了基于序列化属性列表的低级（libSystem）进程间通信机制。）
XPC connection interrupted
进程间通信被中断，主要是由于线程阻塞的问题。检查App内的线程问题
