Subscribing to messageService while in airplane mode (wifi also disabled) crashes device

General
1 

 private func subscribe(channel:String) {
 
 self.channelStatus = .Connecting
 
 let subscriptionOptions = SubscriptionOptions()
 
 // Set polling interval to two seconds
 BackendlessManager.sharedInstance.backendless.messagingService.pollingFrequencyMs = 2000
 
 BackendlessManager.sharedInstance.backendless.messagingService.subscribe(channel,
 subscriptionResponse: {(response : [AnyObject]!) -> () in
 //print ("Channel \(channel): response")
 
 let messages : [AnyObject] = response
 
 for object in messages {
 if object is Message {
 let message = object as! Message
 print ("message: \(message.data)")
 }
 }
 
 self.channelStatus = .Connected
 
 // Post channelStatus Notification
 NSNotificationCenter.defaultCenter().postNotificationName(kBLChannelStatus, object:self)
 
 },
 subscriptionError: { (fault : Fault!) -> () in
 print("Messaging Error (ASYNC): \(fault)")
 
 self.channelStatus = .Disconnected
 
 // Post channelStatus Notification
 NSNotificationCenter.defaultCenter().postNotificationName(kBLChannelStatus, object:self)
 
 // Try to reconnect
 self.start()
 },
 subscriptionOptions: subscriptionOptions)
 }

Calling this method while the iOS device is in airplane mode (and wifi disabled), the app crashes at line 40 (subscriptionOptions: subscriptionOptions)

2

Hi Barry,

What is your expectation when calling any of the network APIs (and this one in particular) when the device has no internet connection?

Regards,
Mark

3

Hi Mark,

Well the thing I don’t expect and surely not want is the application to crash. Even if I check if there is a connection available before calling it, the connection could have dropped just after the check and the method would still crash the app.

I expected a Fault with a code telling me that there is no internet connection.

What are your thoughts on this subject?

4

Hi Barry,

The same thing could happen inside of our implementation: check internet connection availability, then connection drops right before we do the call.

I agree with you that the fault block should be invoked if there is no connection. We will revisit the implementation to see if that can be done.

Regards,
Mark

5

Hi Mark,

Well other api’s just give a timeout when the connection drops while initiating / or transmitting data. So far I could never reproduce a crash while using networking libraries like Alamofire / AFNetworking / Starscream (we have tested a lot with unstable / dropping connections), maybe have a look at how they implemented it?

Thanks a lot,

Barry

6

Hi Mark,

Any update on this situation?

Thanks a lot,

Barry

7

Barry,

It is assigned to a developer to reproduce and to fix (if confirmed as a problem).

Regards,
Mark

8

Hi Mark,

Thanks for letting me know. Just for your info: You other network calls don’t crash when in airplane mode, even not when enabling airplane mode while calls are being made.

As a workaround I now check if there is a connection before trying to connect, but this should really not be necessary in my opinion.

Anyway: Thanks once again for you support!

9

Hi Barry,

So it is just the messaging calls that cause the problem?

Regards,
Mark

10

To be more exact: The call to messagingService.subscribe.

Everything else works perfectly so far.

11

This issue is fixed, you could update the latest Backendless SDK via CocoaPods (3.0.31 release) or from ios-SDK github (CommLibiOS and backendless).