From the Channel Rack choose the ' IAA/Audiobus' module.

Otherwise Audio from FL Studio Mobile will stop when you switch to other Apps.

Open FL Studio Mobile and from the SETTINGS tab make sure the ' Enable background audio' switch is ON.The connection is made through the Input/Output IAA/Audiobus module and you can treat this like any other Synth or FX module. IAA is an Apple audio and MIDI connection protocol to external 3rd party Apps (such as synthesizers and audio effects). This is usually in the Apps own custom settings. NOTE: Make sure any external App you are connecting to has ' Background audio' mode enabled. Open IAA App / Audiobus App - Opens the selected App for editing.However, if that does not work, set them both to the same Channel number. A setting on the 3rd party App of ' Omni' should mean it responds on any MIDI channel (all). If a synth does not respond, make sure its own MIDI Channel settings and ' MIDI Output Channel' match. MIDI Output Channel - MIDI Channel FL Studio sends note/control data out to the App on.Gain - Audio output gain (Volume level).

Select ' Audiobus' when using the Audiobus App. Select the IAA compatible Apps directly from the list. IAA is Apples proprietary standard while Audiobus is a popular 3rd party App with similar functions. This module is an input and output plugin for Audio and MIDI to and from Inter App Audio (IAA) and Audiobus connections. FL Studio Mobile Inter App Audio | IAA Module (iOS ONLY)

Inter audio apps for garageband