Audiobus Inter-App Communication On iOS

I’ve been on a personal “quest” to find examples of iOS inter-app communication. I’ve set up workflows with Pythonista and the apps I use, and I’ve searched for apps that have implemented x-callback-url in meaningful ways. I believe Apple will eventually have to address the need of letting iOS apps better communicate with each other with something more powerful than an Open In... menu.

Today I was sent a link to Audiobus. The developers call it an “inter-app audio routing system” – a way to bring music apps together to avoid sending files back and forth between different apps. It is, essentially, a way to record on an iPhone an iPad using the capabilities of multiple apps at once: with a system based on inputs, outputs, and effects, Audiobus routes audio through specific apps and keeps playing audio from different apps in the background. The videos are really the best way to understand the whole concept behind this solution, as it doesn’t look like anything that has been done on iOS before.

I would love to know the technical details behind this. From what I can gather, Audiobus provides an SDK that developers can use to register their apps as input and output sources, or effects. Once registered, Audiobus creates a “workflow” for these apps and displays a “panel” at the side of an iPhone or iPad, showing the apps that are playing in a single session. I don’t think there’s a time limit on background audio, and it appears the side-panel is also capable of stopping audio from specific apps and switching back to them.

I am intrigued by the possibilities offered by a third-party SDK for better iOS inter-app communication: right now, Audiobus already works with apps like Rebirth for iPad, Loopy HD, SoundPrism Pro, and MultiTrack DAW, and more developers will join the program soon. I’m not sure how the panel concept would translate to tasks that don’t involve audio; however, imagine, say, being able to copy a URL from your browser into your text editor without switching back and forth between them. Or getting a file from the Dropbox app embedded into a Pages document without a tedious variety of multitasking gestures and Copy & Paste menus.

Check out Audiobus here.