Crash in PhoenixTransport iOS 18 only

[udaypatial]

Hi we're seeing a number of crashes on crashlytics in PhoenixTransport. Any thoughts?

Crashed: com.apple.NSURLSession-delegate
0  libobjc.A.dylib                0x9260 objc_loadWeakRetained + 180
1  SwiftPhoenixClient             0x121d0 closure #1 in URLSessionTransport.receive() + 294 (PhoenixTransport.swift:294)
2  Foundation                     0x46c294 <redacted> + 200
3  Foundation                     0x46c404 <redacted> + 84
4  libdispatch.dylib              0x2370 _dispatch_call_block_and_release + 32
5  libdispatch.dylib              0x40d0 _dispatch_client_callout + 20
6  libdispatch.dylib              0xb6d8 _dispatch_lane_serial_drain + 744
7  libdispatch.dylib              0xc214 _dispatch_lane_invoke + 432
8  libdispatch.dylib              0x17258 _dispatch_root_queue_drain_deferred_wlh + 288
9  libdispatch.dylib              0x16aa4 _dispatch_workloop_worker_thread + 540
10 libsystem_pthread.dylib        0x4c7c _pthread_wqthread + 288
11 libsystem_pthread.dylib        0x1488 start_wqthread + 8

[udaypatial]

it happens when we background the app. on backgrounding we disconnect the socket connection. it disconnects but crashes.

[udaypatial]

any idea @davidstump ?

[dsrees]

@udaypatial Is it consistently crashing when you background the app? Can you easily reproduce it?

[udaypatial]

I couldn't reproduce it but crashes quiet consistently on production 10k users affected.

[udaypatial]

the number has increased drastically after we upgraded to the latest version or maybe has something to do with iOS 18

[dsrees]

These are kinda hard to track down. I have a couple of pending weak reference changes that I can push a release to and see if that helps your numbers come down.

[dsrees]

@udaypatial 5.3.4 is available, if you could give it a try and report back.

upgraded to the latest version

Another option is to rollback to the previous version you were using and see if crashes go away. This would narrow down if it was caused by a previous change or if it is specific to iOS 18.

[udaypatial]

@dsrees thanks i'll try this new version and let you know how it goes.

[pouyayarandi]

In this thread, seems CFStream cause crashes in WebSocket.
https://forums.developer.apple.com/forums/thread/769191

Based on the thread, DTS engineer suggests use Network framework instead of CFStream as it's going to be deprecated.

[varun-score]

Hey @dsrees, since Uday recently left our company, I’ve taken over this work. Despite updating to version 5.3.4, we’re still experiencing a high crash rate. Would you recommend rolling back to an earlier version to see if it resolves the issue? If so, which version would you suggest we roll back to?

[dsrees]

In this thread, seems CFStream cause crashes in WebSocket. https://feedbackassistant.apple.com/feedback/15934866

Based on the thread, DTS engineer suggests use Network framework instead of CFStream as it's going to be deprecated.

I'm not able to see any feedback referenced in that link. If you could, could you please copy the relevant snippets?

[pouyayarandi]

Sorry @dsrees, the link was wrong. Thread link:
https://forums.developer.apple.com/forums/thread/769191

from thread:

If that’s the case I recommend that you change that code to use Network framework. Using CFSocketStream for networking is no longer a recommended approach. See TN3151 Choosing the right networking API.

[dsrees]

Hm, fascinating. According to this documentation, it suggests against using URLSession for new websocket code. Since NWConnection has been available since iOS 12, I can see implementing a transport layer with it.

@varun-score I don't know when I'll get to this. You can try implementing your own in your project and passing it as the Transport in your pocket constructor. You can use URLSessionTransport in the client as an example