In my iOS app I am currently using Bonjour (via Network.framework) to have two local devices find each other and then establish a single bidirectional QUIC connection between them. I am now trying to transition from a single QUIC connection to a QUIC multiplex group (NWMultiplexGroup) with multiple QUIC streams sharing a single tunnel. However I am hitting an error when trying to establish the NWConnectionGroup tunnel to the endpoint discovered via Bonjour. I am using the same "_aircam._udp" Bonjour service name I used before (for the single connection) and am getting the following error: nw_group_descriptor_allows_endpoint Endpoint iPhone15Pro._aircam._udp.local. is of invalid type for multiplex group Does NWConnectionGroup not support connecting to Bonjour endpoints? Or do I need a different service name string? Or is there something else I could be doing wrong? If connecting to Bonjour endpoints isn't supported, I assume I'll have to work around this by first resolving the discovered endpoint using Quinn's code from this thread? And I guess I would then have to have two NWListeners, one just for Bonjour discovery and one listening on a port of my choice for the multiplex tunnel connection?

When creating multiple QUIC streams (NWConnections) sharing one QUIC tunnel (using NWMultiplexGroup), is it possible to assign different priorities to the streams? And if yes, how? The only prioritization option I found so far is NWConnection.ContentContext.relativePriority, but I assume that is for prioritizing messages within a single NWConnection?

I am using NWListener and NWBrowser to establish a NWConnection between two local devices. I noticed that if I run the NWBrowser client on the iOS Simulator and create a (single) connection for a result endpoint found by the browser, the NWListener's newConnectionHandler on the destination device is called with three different connections. Is this a bug or just something unique to the simulator? Or should I prepared to handle this in general? And if so, should I just accept the first connection and reject subsequent ones, or pick the last one, or choose the best option amongst them (and if so, how)? Here is an example of the three connections received by the NWListener for the one NWConnection attempt from the simulator: Client connected: [C1 fe80::8bb:e5ff:fe18:bab%anpi0.57383 tcp, traffic class: 700, local: fe80::8bb:e5ff:fe18:b54%anpi0.56395, definite, attribution: developer, server, path satisfied (Path is satisfied), viable, interface: anpi0, scoped] Client connected: [C2 fe80::53:558d:8f79:9a0c%en2.57384 tcp, traffic class: 700, local: fe80::897:b297:76e0:a53%en2.56395, definite, attribution: developer, server, path satisfied (Path is satisfied), viable, interface: en2, scoped] Client connected: [C3 fe80::3c:91d7:b7e:7c2b%en0.57385 tcp, traffic class: 700, local: fe80::1cf2:d1b6:220d:4d8f%en0.56395, definite, attribution: developer, server, path satisfied (Path is satisfied), viable, interface: en0, scoped, ipv4, ipv6, dns]

For a local video streaming app I want to establish both a TCP and a UDP NWConnection. What is the best way to do this using Bonjour? Do I advertise separate Bonjour services for TCP and UDP? Or if I just advertise one (say TCP), what is the best way of creating a new UDP NWConnection to the same device once the TCP connection has been established?

This is both a heads-up to other developers, and a request for workarounds: I noticed that the CoreML image segmentation model in my app crashes when compiling the app with Xcode 13 and running it on an iOS 14 device. Compiling the same app and model with Xcode 12 the compiled CoreML model works just fine when running on the same devices. The crash seems to be caused by CoreML trying to access the MLShapedArray type, which was only introduced in iOS 15 (see stack trace in screenshot). So if you have an app using CoreML, make sure you test on iOS 14 devices before submitting a new build using Xcode 13. For Apple folks, I filed a Feedback on this a little while ago (and of course heard nothing back). The ID is 9584636. I had hoped this issue would get fixed before the Xcode 13 release, but unfortunately it is still there in the GM build. Any workarounds (aside from 'keep using Xcode 12') would be appreciated.

After a user complained that they could no longer load partially transparent PNG images in my photo compositing app, I eventually tracked this down to a bug in iOS 15.1 (tested on beta 2). When the user selects a PNG image in the PHPickerViewController, the returned NSItemProvider reports having a file for the "public.png" UTI (and only that one). However when requesting data for that UTI, the system actually returns JPEG image data instead. Just a heads up to other developers who might run into this. Hopefully it will get fixed before 15.1 ships. I reported it as FB9665280.

A heads up to other developers using CoreML: Make sure to test your apps and CoreML models on an A15 device like the new iPhone 13. My app uses CoreML for a custom image segmentation model. Which runs fine on all previous devices, but hangs/crashes on my iPhone 13 Pro, and (based on customer reports) on other devices with the A15. The error seems to happen when part of the model is executing on the Neural Engine. I worked around it for now by not using the Neural Engine when running on A15 devices. modelConfig.computeUnits = UIDevice.current.hasA15Chip() ? .cpuAndGPU : .all where hasA15Chip() is a custom helper method. For Apple engineers: I provided additional information in FB9665812.

We have a reasonably complex mesh and need to update the vertex positions for every frame using custom code running on the CPU. It seems like SceneKit is not really set up to make this easy, as the SCNGeometry is immutable. What is the easiest (yet performant) way to achieve this? So far I can see two possible approaches: 1) Create a new SCNGeometry for every frame. I suspect that this will be prohibitively expensive, but maybe not? 2) It seems that SCNProgram and its handleBinding... method would allow updating the vertex positions. But does using SCNProgram mean that we have to write all our own shaders from scratch? Or can we still use the default Scenekit vertex and fragment shaders even when using SCNProgram?