The run loop that the interruption listener callback should be run on. Pass NULL to use the main run loop.
置 NULL ,是使用默认的the main run loop;(当在监听器回调的时候停止循环)
inRunLoopMode
The mode for the run loop that the interruption listener function will run on. Passing NULL is equivalent to passing kCFRunLoopDefaultMode(kCFRunLoopDefaultMode来持有对象,在应用或线程闲置的时候这些对象被监控).
The interruption listener callback function. The application’s audio session object invokes the callback when the session is interrupted and (if the application is still running) when the interruption ends. Can be NULL. See AudioSessionInterruptionListener.