Inter-App Audio (IAA) is a deprecated[1] technology developed by Apple Inc. which routes audio and MIDI signals between applications on the iOSmobile operating system. The technology was first introduced in 2013 in iOS 7 and deprecated in 2019 with the release of iOS 13.
Scope
Inter-App Audio is a host-plugin technology. An IAA host application connects to a node application to send and receive audio, MIDI, timeline information, and other signals.
Node applications
Node applications can be of the following types:
Instruments (can receive MIDI signals and produce audio signals)
Generators (can produce audio signals)
Effects (can receive, transform and send back audio signals)
Limitations
At the moment, audio signal routing is only possible with a sampling rate of 44 1 Hz.
Deprecation
Inter-App Audio was deprecated in 2019 with the release of iOS 13 in favor of the third version of Audio Units.[2]