Chapter 4: iOS Music Tools

OK, it’s time to get down to the specifics of making music with your iOS device.

Starting with this chapter, I’m going to do things a little bit differently. If I were to post the text of the original chapters, in many cases I would be posting completely useless information that I would immediately have to correct, simply because so much has changed. Instead, I’ll try to follow the same basic structure of the original while providing more up-to-date information.

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It’s time to get down to the specifics of making music with your iOS device. For starters, you’ll need to get your head around the tools you’ll be using to route audio and to share audio files between apps and devices.

Getting Sound From A to B

The first major consideration for working with iOS music apps is deciding how to get your audio where you need it. For streaming audio between apps, there are currently three options: Audio Units, Inter-App Audio (IAA), and Audiobus.

Audiobus

Audiobus was the first solution for streaming audio between apps, and completely changed iOS music making when it launched. Audiobus originally required app developers to add specific code to their apps to make them Audiobus-compatible. After the launch of Apple’s Inter-App Audio, Audiobus was reworked with IAA at its core, and Audio Unit support was added once that became available in iOS 13. The result is a large catalog of over a thousand Audiobus-compatible apps.

Audiobus is a third party app, and does require some in-app purchases to achieve full functionality. Using Audiobus means running the Audiobus app as a host for other apps, so things become a little more complex when you’re using it in conjunction with another host DAW.

Inter-App Audio

Inter-app Audio was released by Apple in 2013 with iOS 7, allowing developers to basically do what Audiobus was doing, but with a manufacturer provided and supported framework. IAA still requires a host app to route audio between compatible apps, and most iOS DAWS can act as IAA hosts.

Audio Units

Audio Units are a cross-platform host-plugin architecture, introduced with iOS 13 in 2019. As part of the system-level Core Audio framework, Audio Units allowed desktop developers to port their existing plugins more easily to iOS and develop apps that would work on both mobile and desktop. The launch of Audio Units also marked the official deprecation of IAA. Notably, when Apple launched Logic Pro for iPad in 2023, they included support for Audio Units, but not for apps built on IAA.

Inter-Device Audio

If you have multiple devices and/or you are using your device in conjunction with a computer DAW, you will also want to consider the best method of pushing audio back and forth. Using a dedicated hardware audio interface is almost always going to be the best option for maintaining the best sound quality while ensuring low latency. Not all audio interfaces will work with iOS devices, so do your homework, and make sure you have a Camera Connection Kit.

With the exception of the iConnectivity interfaces mentioned below, you’ll probably want a dedicated audio interface for each device you hope to integrate into your workflow. My current number one choice is the M-Audio AIR 192|14 ,which offers 8 inputs and 4 outputs. The extra set of outputs gives the extra flexibility of setting up an effects loop or sending a separate monitor mix.

There were a number of software/app solutions for routing audio over USB or wireless when I published the book back in 2015, but as of this writing, there seem to be no working solutions for bidirectional audio without one or more hardware audio interfaces.

Of course, as soon as I published this, I found Wireless Audio AUv3 by Secret Base Design, who were involved with some of the previous solutions I mentioned, but I haven’t tested it myself.

iConnectivity

It’s worth mentioning the iConnectivity Audio4+ and Audio4c audio interfaces which support 2 devices at once for bilateral audio and midi. The Audio4+ was my go-to interface for many years, but the control software is out of date and partially unusable at this point, and the model has been phased out in favor of the Audio4c, which I have no experience using. I chose the M-Audio over the Audio4c when it came time to upgrade because I needed more than two Hi-Z inputs (I have 5 channels of audio coming from my guitar pedal board), but I may pick one up in the future.

Inter-Device Audio and Midi

As of iOS 9, you can connect your iOS device directly to a Mac via USB and enable it as an audio and midi device. While MIDI does flow both directions, unfortunately audio only flows from your device to your Mac.

The Loopback Trick

Here’s a handy trick for recording apps that don’t have Audio Unit, Audiobus, or IAA support if you don’t use a desktop DAW or multiple devices. If you have a hardware audio interface which works with your iPad, you can connect the output jacks to the input jacks on the interface. You’ll want to ensure that your DAW app is set so that it doesn’t monitor the incoming audio signal or you will cause feedback. By connecting your headphones to the audio interface, you will be able to monitor the audio coming from the legacy app (or a new app from a clueless developer).

One of the most common USB audio interfaces used by iOS musicians is the Behringer UCA-202 or UCA-222. These devices are great because they are inexpensive, compact, and can be powered by your device.

Sharing Audio Files

Starting with iOS 8, Apple introduced the ability for apps to register themselves as document providers for other apps without the need to implement a third-party API. This is now the best way to move WAV files around between apps, and honestly the only method I’ve used for years.

Apple introduced the Files app with iOS 11, finally making iOS feel more like a real OS with basic file management. By clicking on the “On My iPad” location, you can navigate to files for specific apps stored in the shared file system.

AudioShare is still the gold standard for managing and working with audio files on iOS, and gets its own folder under locations. Most apps which allow for importing files support opening files from the Files app or AudioShare.

Another method of file sharing uses inter-app file sharing via export or “open in” features found in supporting apps. Generally speaking, choosing the “Open in...” option from an export menu will bring up a list of compatible apps that can receive your file.

In the early days, there was a lot of copying and pasting of files using the general clipboard or apps like AudioCopy, but it seems kind of silly now that there is a more robust system of file management.

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That’s it for this chapter. The next six chapters will dig more deeply into specific types of apps and techniques.

Feel free to leave a comment if this has been useful, or especially if I’ve missed or misrepresented anything.

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