I've been waiting for more updates to the user documentation as well. Actually got feedback from Apple granting the vendor ID we're looking to use, but still no luck in getting a basic init/free extension working.

Okay, just to bring anyone viewing this up to speed. I've been trying a few different directions for this and most avenues seem to be dead ends, or at least in my case. One test that has partially worked is to take the IOKit and headers from the iPhone private framework and add that to the project. Which I know won't pass muster if sending to the AppStore. This is just for my own testing at this point. I create a notification port with IONotificationPortCreate and IONotificationPortSetDispatchQueue I can set a matching service using IOServiceMatching with the vendor and product IDs which I can retrieve from the Mac, and a callback routine with IOServiceMatchingCallback. When incorporated into an app and run, connecting and disconnecting the SparkFun Serial Basic Breakout board, with invoke the callback function with details of the device. This is a small step in at least the board is now being recognised when connected and removed from the iPad Pro. Sending or receiving data to or from the board is the next step. Any help in this regard would be very helpful. The SparkFun Serial Basic Breakout board allows the Tx and Rx to be connected together allowing a sort of echo function. This works when connected to an Apple Mac, this I'm looking to as the next small step. If anyone know a better solution please let me know.

This was last posted to 2 years ago, and would be interested in peoples opinion on the matter now. I've had a few internal birdies tell me that Objective-C will be put out to pasture in the near future once all frameworks are ported over, and from what I'm hearing that is/or has nearly been completed. Possible mention at WWDC 2022, with 3 years to finally pull the plug. The issue is Apple having to support 2 development languages and along with that all those people involved in keeping both system alive. You will find that new frameworks will be only supported in Swift so eventually everyone will have to be using Swift. For those supporting older apps and code bases, it'll be like the move to 64bit iOS apps and the removal of 32bit apps from the store. If you still need to support internal 32bit then an older Mac with older OS and Xcode would be needed. The removal of Objective-C seems to be tied in with the move to Apple Silicon. I could be wrong on that point, but then again, makes sense.