Probably way too late but perhaps someone else will benefit from the discussion. I have observed that the system will always jump to the recently plugged-in microphone. I assume this is because they assume that a person who just plugged in a microphone wants to use said microphone immediately. My suggestion is to monitory the route change notifications and re-assert your wishes by calling setPreferredInput again. I have not tested this but give it a try.

The Apple defect for iOS was solved last year. If you are still having issues on iOS, make sure you are running the latest version of iOS as a first step. If that requirement has been met, you have some other technical issue prevent preventing your driver from properly being recognized by the system. If you are using macOS, there may be other issues such as your Xcode configuration, or not having your system properly set up for driver development. I don't have all the details for macOS, but the documentation provided by Apple should help in this instance. It might help if you created a separate issue perhaps linked to this one where you completely describe your situation and the problem you're experiencing. Be sure to include the code and configuration snippets so we can see exactly what you are doing in order to properly register and activate your driver.

I too have the same requirement. With my USB driver I cannot tell the difference between the device being unplugged and the driver not being activated via the Settings app. I need to be able to direct the user to flip the switch when I know for certain that it has not yet been flipped. Neither the IOKit or SystemExtensions frameworks are available in iOS. Does anyone know of a workaround for this issue?

If I do what I think I need to be doing to unmap the memory, when I try to open the service again, it fails. If I skip the step where I do that unmapping, the service opens successfully. Are you saying everything works if you don't unmap the memory? That is, when you open the device again without attempting to un-map memory, can you communication successfully to the device and proceed as normal? The way this is worded, it is unclear to me.

Yes it does (assuming I'm correct about AVCaptureDevice being part of the AVFoundation framework). I have a USB connected camera that I use to capture video and still images using the AVCaptureDevice APIs.

I am also having an issue with this change in my code. Why doesn't switching from .ascii to .utf8 work? Doesn't this allow for the high bit to be set? Sorry for the ignorance but I look forward to Quinn's answer.

This is now an issue with iPadOS 18. In iPadOS 17.7 my driver shows up in settings just fine. After recompiling with Xcode 16 and installing my app (containing my driver) on iPadOS 18, the app shows up in settings but the driver-enable button is missing from Settings. When I plug-in my custom USB device, the app cannot detect it.

Did you ever figure this out? I've been doing the same thing. I don't get any crashes but when I hand the buffers of to LiveSwitch for playback, there is not audio signal. I receive the buffer from a tap on bus zero. I send the buffer to the publisher. Buffer is received, potentially by up to two consumers (currently one). Buffer has to be converted using AVAudioConverter from Float32 to Int16, which is required for consumption by LiveSwitch APIs. Buffer memory converted to NSMutableData (required by LiveSwitch) Buffer wrapped / converted in FMLiveSwitchAudioFrame. Buffer raised to LiveSwitch for processing. Result: No signal.

Can Apple weigh-in on this issue? I'm currently receiving samples as Float values and I also need signed 16-bit integer values. I don't want to convert these on the fly if I don't have to or if I can somehow get it for free at the source. Apple: How do we make this happen in code?

@enodev Thank you for your response. However, the answer seems to skirt the question. I don't want to use both Actor and DispatchQueue, perhaps in some sort of wrapped or nested form. I want to use one in place of the other. Your answer would seem to imply that this is not possible and that using an Actor with AVFoundation APIs that must run on something other than main, for blocking reasons, would still need a DispatchQueue.

Solved. Must call setNeedsDisplay from the main thread.

This problem has been solved. Please see this thread for details. https://developer.apple.com/forums/thread/751490

Kevin, thank you so much for responding. My entire dev team just got together on a video call and spent 3 hours trying everything we could to figure this out. No personal reflection on you but Apple MUST do better. The information you provided above jives with most of what we discovered. The solution for us was to switch to automatic and also change the idVendor value from a String to a Number when moving from an wildcard value to a literal value. This appears to be necessary when putting a real Vendor ID in the entitlements file. This was a lot harder than it should have been.

I have the same question with regard to the USB transport entitlement. I've added my vendor id to the appropriate entitlement files but my binary fails validation when trying to upload it to the store for distribution. The embeded.mobileprovision file in the generated archive shows an asterisk instead of my approved Vendor ID. How can I make sure the embedded provisioning file has my Vendor ID?