Unsubscribe from channel after even trigger leads to crash

[radumihaiu]

I listen for an event and when that even triggers I unsubscribe from the channel. This has about an 80% chance to produce NSGenericException*** Collection <__NSArrayM: 0x1523c7340> was mutated while being enumerated.

This is the stacktrace that bugsnag produces

Pods/libPusher/Library/PTPusherEventDispatcher.m:68:3-[PTPusherEventDispatcher dispatchEvent:]
Pods/libPusher/Library/PTPusherChannel.m:167:3-[PTPusherChannel dispatchEvent:]
Pods/libPusher/Library/PTPusher.m:381:5-[PTPusher pusherConnection:didReceiveEvent:]
Pods/libPusher/Library/PTPusherConnection.m:158:3-[PTPusherConnection webSocket:didReceiveMessage:]
Pods/SocketRocket/SocketRocket/SRWebSocket.m:753:9_30-[SRWebSocket _handleMessage:]_block_invoke

The workaround I have in order for it not to crash is to add a delay to the unsubscribing of about 1s.

[lukeredpath]

Thanks for the report. I can see why unsubscribing in an event handler causes this - unsubscribing from a channel removes all bindings from the channel however the event dispatcher iterates through its bindings when it receives a matching event - when the event handler is called it will be mid-way through enumerating the bindings.

A simple solution would be to copy the bindings and enumerating over the copy, but I'll have a think about whether there is a better solution.