问题
Is there an easy way to read current dB sound level values of what iOS it putting out to the speakers / or from background music that is playing?
回答1:
No. An app can not get the audio output levels for the sound that any other app, for instance a background music player, is currently playing.
来源：https://stackoverflow.com/questions/12661308/how-to-get-the-current-output-db-values-of-background-music-to-display-a-sound-l