You can dynamically access audio processing plug-ins, known as audio units, from your iOS application. This lets you add a variety of useful, prepackaged audio features and take advantage of the low latency that audio units offer.
iOS ships with audio units that support mixing, equalization, format conversion, and I/O for recording, playback, or live chat. Read this document to learn how to access any system-supplied audio unit from your application.
This document is for iPhone developers who want to use audio features provided by system audio units. Before reading this document, you should already be comfortable with iOS development as described in iOS Application Programming Guide and iOS Development Guide. For a tutorial introduction to creating programs for iOS, read Your First iOS Application.
Audio units in iOS are a type of Core Foundation plug-in. If you are unfamiliar with this technology, read Plug-ins. If you are new to Core Audio, read Core Audio Overview.
Audio units complement other, higher-level audio technologies available in iOS, among them OpenAL, AV Foundation, Audio Queue Services, and iPod library access. To get a feel for which audio technology best addresses your application’s needs, see Getting Started with Audio & Video.
This document includes the following chapters:
“About Audio Unit Access”—Introduces audio units and audio processing graphs, and how your application can access them.
“Accessing Audio Units”—Provides details on how to access an individual audio unit.
“Creating Audio Processing Graphs”—Provides details on how to create an audio processing graph, an object that manages a chain of audio units.
An appendix, “System-Supplied Audio Units in iOS,” lists the system-supplied audio units in iOS along with their programmatic identifiers.
Take advantage of these other resources as you’re learning about loading audio units:
aurioTouch—A sample application that demonstrates simultaneous input and output using the I/O unit.
Audio Unit Framework Reference—Reference documentation for the framework you use for finding and using audio units.
Audio Unit Processing Graph Services Reference—Reference documentation for using audio processing graphs.
Core Audio Overview—An introduction to the architecture, philosophy, and programming idioms of Core Audio.
Core Audio Glossary—Definitions for terms used in this document and throughout the Core Audio documentation.
Last updated: 2010-01-20