IOS10 voipEnabled = true not work

[hai00jiao]

when my app enter background , the socket connection is paused, after the app enter foreground again, the request data arrive together.
UIBackgroundModes

voip
audio
fetch
remote-notification

[alphatroya]

Confirm, iOS 9 devices receive data normally, but iOS10 data receiving paused after going background. socket.voipEnabled enabled, background modes too.

There is any temporary workaround for this?

[alphatroya]

Fix it by launch background task in applicationDidEnterBackground method

[nitrag]

I don't think @alphatroya suggestion works, does it?

[Laptopmini]

FYI, using VOiP Background mode to keep the websocket connection alive goes against Apple TOS/Guidelines. It is a misuse of background modes, which is grounds for rejection from the AppStore.

[daltoniam]

Yeah I don't know why iOS 9 -> 10 caused this to stop working. That being said, @Laptopmini is right in general use cases. This was added for a very specific case of in house apps and someone using a WebSocket in a VOIP setup. I will try looking into this as time permits and PRs are welcomed.

[nitrag]

I've recently had an in-depth conversation with Apple DTS on this.

Simply, you have to use PushKit/APNS. The "Legacy VOIP API" as they call it (which would hand the socket over to the system to wake up your app if communication arrived) was deprecated in iOS 9 and removed in iOS 10. As such, there's no way to keep a socket connected while in the background and that flag no longer has any effect as OP described.

You can buy yourself ~3 min by launching a background task on applicationDidEnterBackground but that's all you get and it cannot be called again without the app entering the foreground (by the user).

@daltoniam nothing to look into I'm afraid, you should plan to pull the functionality.

[daltoniam]

@nitrag nice write up and thank you for that info! I'll do that next version (and update the documentation accordingly).

[sahara108]

If the app is woken up by the push notification, the socket will be closed after around 40 seconds with this error Socket being disconnect with error Optional(Error Domain=NSPOSIXErrorDomain Code=57 "Socket is not connected" UserInfo={_kCFStreamErrorCodeKey=57, _kCFStreamErrorDomainKey=1}). In my solutions, I will force the socket to re-connect when there is another push after socket being closed.

[johnnynanjiang]

Hi @daltoniam one scenario I discovered is that

1. websocket is connected in foreground, ping/pong going on
2. websocket goes into background, ping/pong is paused
3. websocket comes back to foreground, ping/pong continues for a short time
4. websocket gets disconnected with error nil

Not sure if 4. is expected or not, can you please advise? Thanks.