iOS/Mobile Safari: onLeave not triggering in the client-side

[endel]

Reported by Josh via Discord (https://discord.com/channels/525739117951320081/526083188108296202/910023542702223380)

Hey there!
Does anybody know why onLeave might not be called on the client? Testing on iPhone and turning off wifi + cellular doesn't call the method.
Only way I've found to call the onLeave method on the client is to kill the server while still connected to it.
Any ideas?

[endel]

Josh just shared his reproduction case here https://github.com/jorasso/colyseus-examples

Okay, @endel I was able to get a sample project showing the onLeave issue.
The steps to reproduce are in the README and there's a video there too.
But you'll see the onLeave isn't being called when disconnecting from the internet, only when being removed from the room.
The repo is here: https://github.com/jorasso/colyseus-examples
Thanks so much and let me know if you have any questions!

[lpsandaruwan]

This functionality seems to be working fine in Chrome/Windows. I will investigate in Safari/Mac.

[lpsandaruwan]

Hi @endel,

onLeave seems working fine in Mac/Safari and IOS/Safari. I've tested on both platforms. Please check this video.

[endel]

Hi @lpsandaruwan, I see your video and I think by clicking on "disconnect" does not have the same effect as fully disconnecting from the wi-fi network as described by Josh

Testing on iPhone and turning off wifi + cellular doesn't call the method.

[joshfeinsilber]

Hey y'all!

I have a little more information on this. It looks like the disconnection detection is only occurring on the server.

Visit here and scroll down just a bit as it lists steps to detect disconnects on the client.

However, looking at the Websocket Transport, there currently isn't anything checking for the ping messages sent from the server. I also didn't find anything in onMessageCallback.

In our project, we're going to start looking into implementing this. If it works out, we'll make a pull request. However, I suspect this will involve adding a new option on the client for the duration of the interval (should be just a little higher than pingInterval on the server).

We also might try to go a bit further by instantly detecting an offline event and calling the close event immediately.

But based on me looking around a bit, I believe that's why this issue is occurring. There's nothing on the client currently that detects disconnections.