I tested my app in the background by setting the alarm and watching a video, and my alarm was correctly ringing when I was watching the video.
Even when I removed my app from the background the alarm was ringing. Now I wonder if I correct understood Apple's reply. Can any one decode the reply?
We found that your app uses a background mode but does not include functionality that requires that mode to run persistently. This behavior is not in compliance with the App Store Review Guidelines.
We noticed your app declares support for audio in the UIBackgroundModes key in your Info.plist, but no audible content is played when the application is in the background. While your intention may have been to provide this functionality, at the time of review, we were not able to play background audio for your app.
As indicated in the iOS Application Programming Guide:
"This key is intended for use by applications that provide audible content to the user while in the background, such as music-player or streaming-audio applications."
Therefore, it would be appropriate to provide audible content to the user while the app is in the background or remove the "audio" setting from the UIBackgroundModes key.
What don't you understand about it? It is very clear that you gave a UIBackgroundMode of "audio" but didn't play any audio in the background.
You can enable Background Modes from capabilities and there check audio and background fetch . Then your app is able to access all audio streaming from the background.
来源：https://stackoverflow.com/questions/10646034/why-did-my-app-get-rejected-because-multitasking-apps-may-only-use-background