The AudioUnit user presets system has ceased to work as expected in iPadOS 14

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Created Nov ’20

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The AUAudioUnit in my app uses the user presets system that was introduced with iPadOS/iOS 13.

The user presets system worked well in iPadOS 13, and it worked in at least one of the pre-release beta versions of iPadOS 14. However, it has not worked since iPadOS 14.0 was released.

The problem is (superficially, at least) that:

saveUserPreset no longer writes preset files to the app's Documents folder, but the method doesn't fail either.
The userPresets array, which typically contains the presets that were deserialised from the files stored in the Documents folder, is invariably empty. The presets that the array would contain prior to upgrading from iPadOS 13 are no longer accessible.

In other words, prior to upgrading to iPadOS 14, my app could save user presets using the saveUserPreset method and subsequently access their contents from the userPresets array. Since upgrading to iPadOS 14, the userPresets array is invariably empty and the saveUserPreset method no longer saves presets to the Documents folder.

Has anyone else experienced this problem?

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Answer 1

kennylovrin OP

Jun ’22

I would like to bump this one as I suspect I have the same or a similiar issue..

I'm trying to implement user presets, and when calling saveUserPreset: I get no error, but it also doesn't update the userPresets property, and I get no notification of any sort as per the documentation (https://developer.apple.com/documentation/audiotoolbox/audio_unit_v3_plug-ins/incorporating_audio_effects_and_instruments?language=objc). Essentially it behaves more like it just fails silently.

I've downloaded the demo project on the link above, and when I run that iOS app, selecting the AUv3Filter demo component I can save user presets, so technically I can see that it is possible.

However, I cannot for the life of me find what it is that specifically makes it work, as there are no custom implementations of saveUserPreset. I am starting to suspect it's a configuration issue, but I can't figure it out.

Any ideas at all would be helpful.. :)

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