Stops the audio engine and releases any previously prepared resources.
- iOS 8.0+
- macOS 10.10+
- UIKit for Mac 13.0+Beta
- tvOS 9.0+
- watchOS 3.0+
When called, this method stops the audio engine and the audio hardware, and releases any resources allocated by the
prepare method. When your app doesn't need to play audio, you should pause or stop the engine (as applicable), to minimize power consumption.