In my app I'm using MKNetworkKit to make requests to my server and also make direct calls to Facebook using Facebook SDK. Sometimes (once in a few days) I get an odd issue: all network requests from my app stop working (both to my server and Facebook). I can't figure out what steps exactly cause this. When I have the issue I check other apps / Safari from my phone and internet connection is OK. If I close my app, wait for a couple of minutes and open it again then everything goes back to normal. I'm using WiFi for testing. What can cause this?
It seems to be exactly like in this question: iPhone app gets into a state where network requests never complete , although I don't use MonoTouch.
UPDATE:
I do receive callbacks from MKNetworkKit saying "Request timeout" (I have 10 seconds request timeout in MKNetworkKit settings). And I don't receive callbacks from Facebook.
Related
I'm using the Wink API to control lights and thermostats etc. In the API you can subscribe to device topics to receive events such as when a light is turned on or off. This is handled through PubNub. I have this all working except that the events stop being sent if I leave the system overnight.
If I try to "manually" toggle a light by tapping the physical switch then normally an event is fired and received by my application via PubNub. Restarting my application and thus reconnecting to PubNub does NOT resolve the issue. The only way I've found to resolve the issue is to open the Wink app itself. Nothing else needs to be done but to open the Wink app. Then if I manually toggle the switch the event will show up and be received by my application. This solution works even if I don't restart my application.
There appears to be some sort of wake or keep-alive going on. Although I don't see anything in the Wink API docs that state such. There is also nothing sent from PubNub during this downtime. I have logging being sent out for the status(), message(), and presence() callbacks and nothing is logged from these overnight. Therefore taking all the above into account I believe the issue resides on the Wink side of things.
Unfortunately, Wink does not provide developer support. The Wink app is obviously doing something but because the transactions are encrypted it is unknown what it is doing. Also my test cycle is 8 hours long currently so it is difficult to debug this by trial and error. I'm working to see if this "timeout" is shorter than the overnight 8 hours I've experienced so far. i've also tried power cycling my Wink Hub yesterday but that did not resolve the issue.
Anyone else run into this issue? How do you keep subscriptions alive so that they are always sent?
I have an app that lets the user send messages with images. A user might hit send, then immediately close their phone or switch to another app.
We were running into an issue that if there's temporarily a bad network connection the message would fail to send. We switched to using NSURLSession backgroundConfigurationWithIdentifier so that backgrounding the app doesn't immediately time out the running request. We switched to using this for all our api requests, thinking that it wouldn't hurt for every request to able to continue in the background if the app were closed at the wrong time.
Fast forward a couple weeks we're noticing all requests seem slow. Using wireshark I just discovered that this background session seems to use a new http connection per request, meaning it requires setting up a TCP connection and new TLS handshake for every request, which was adding a ~500ms latency on every request in our app. This is a pretty big deal but I can't find this behavior documented anywhere, including the link above or Apple's background transfer considerations.
So my question is, is this behavior expected, or am I doing something wrong somewhere? Is there an easy way with NSURLSession to make an HTTP request that will use an existing keep-alive connection if there is one, but can fall back to the backgroundConfiguration if the app gets moved to the background?
NSURLSession is the recommended way to fulfill your use case. Have you tried setting backgroundSessionConfig.discretionary = true
iOS Reference
A Boolean value that determines whether background tasks can be
scheduled at the discretion of the system for optimal performance.
If that doesn't help, I recommend filing a bug with iOS.
As a slightly open question: Can/how does one send a network request every 5 minutes from a minimised iOS app?
In our case, we want to make sure that a certain message written when offline is sent as soon as the user regains internet access, even if the app is minimised.
Attempts at a solution
Most people are thinking down the 'app posting it' line, which hits the 3 min limit as mentioned.
Is there anything around the server pinging the app (perhaps with a notification) to trigger the app to respond with the required information?
I have encountered a rather strange behavior when trying to implement download functionality on iOS. The download implementation works fine in that it finishes successfully, can run in the background, and file is stored on device. However during a download, I can turn of wifi to let the task switch to and continue on cellular network (or just start the download using cellular). This behaves as aspected. But when I enable wifi again, the download never seem to switch back to using wifi. The device is connected, and the wifi-connection-bars displays at the statusbar. Using rechability functions to check what connection that is available will even return Wifi, but the download seems to be stuck at using cellular.
The way I am detecting this is looking at the Usage stats in the system settings. The cellular data usage will rise in sync with the pending download, and continue to rise until the download is finished (even if wifi is turned on again).
I have tested with both Alamofire and by using NSURLSession and NSURLSessionDownloadTask directly, and they both behaves similarly. I have also seen this behavior in two completely seperate projects, on multiple devices, in iOS 8.4 and 9.1, when the apps are in the foreground or the background, and even AppStore behaves like this when downloading apps!
Has somebody else experienced this?
And if so, did you find any way to gracefully switch tasks back to wifi?
Thanks in advance.
This is normal behavior. Adding a new network interface (e.g. turning Wi-Fi on) doesn't stop existing TCP connections. They will continue until the original network interface goes away.
If you want to pause the request and reconnect when Wi-Fi becomes available, you'll need to call cancelByProducingResumeData: on the task, then create a new request with that resume data to restart the request from where it left off. That new request will go over the currently active network interface, which would typically be the Wi-Fi interface if Wi-Fi is up and running.
Before you stop the existing request, though, I would suggest trying a probe request for something like Google's generate 204 or one of Apple's captive portal detection URLs, to ensure that Wi-Fi really is working.
I have an issue with a single (at least for now) iPhone not being able to connect to websockets. Unfortunately I don't have access to the device and I can't run more tests on it at the moment, so no proper network dumps or anything else deeper level debugging available. Can't test on other network connections either at the moment.
Everything works perfectly with Chrome 45, Firefox 40, Chrome 45 on Android (many devices), Safari on iOS9 (device A), Safari on iOS8 (device B) etc. No errors, no cutoffs, nothing. Just works.
My websocket server runs on IIS 8.5 / ASP.NET, created as an API controller with the typical way (PullHandler is an async Task whileing until connection closes)
if (HttpContext.Current.IsWebSocketRequest)
{
HttpContext.Current.AcceptWebSocketRequest(PullHandler);
return Request.CreateResponse(HttpStatusCode.SwitchingProtocols);
}
else
return Request.CreateErrorResponse(HttpStatusCode.BadRequest, "Bad request");
This should not cause any issues, especially this one. The client side JavaScript is also the simple
new WebSocket("ws://" + window.location.host + "/api/Some/Endpoint);
I am using plain HTTP, no SSL/TLS.
When trying on iPhone device X with iOS9 (13A344, not entirely sure of which model) it just can't get the connection. I am also using SignalR which automatically goes into longPolling transport on this device. With others it's nicely on webSockets transport.
Quick testing on UK Orange 3G connection showed on my HTTP logs that for some reason the request for my endpoint has gone to the else branch, like something had stripped the upgrade headers away.
GET /api/Some/Endpoint 80 - Mozilla/5.0+(iPhone;+CPU+iPhone+OS+9_0+like+Mac+OS+X)+AppleWebKit/601.1.46+(KHTML,+like+Gecko)+Version/9.0+Mobile/13A344+Safari/601.1 - 400
Status 400 is clearly showing the bad request that my code is sending if the request is not a proper websocket request. I don't know if there could be some transparent proxy, that could explain this. The 400 response was received without any delays.
But this was a problem also through wifi on the same device. Again, a laptop with OS X and Safari had no issues on the same wifi to connect to SignalR and my websocket server. Only the iPhone had issues. On wifi I didn't get any attempts to connect on the logs and SignalR also immediately went into longPolling transport. The wifi apparently used Virgin Media's network based on IP address.
On wifi there is first an open event. Then after some time there is a close event with status 1006, which is abnormal termination without a close packet. My code tries to connect again and the same happens. Strangely there is no log entry at the web server, but it might just be Safari's way to post the open event even though an actual connection was not established and after a timeout it sends the close event.
The device should not have any proxies set up and other browsing works without issues. Unfortunately I couldn't get any information about any other site that would use websockets working or not on that device.
Has anyone run into this kind of situation? I do understand that the 3G might just be a misbehaving proxy, but the wifi issue cannot be explained with that.
Just want to expand the universe for this issue.
I Have an app that runs great in simulator. App has both http Jason IO and web socket IO.
Now that I can target my iPhone and not the simulator. App on iPhone successfully does the http Json stuff but not the web socket stuff.
While I am not using safari and js my symptoms are very similar to yours. I am using Xcode 7 to generate code that targets to iPhone 5 using iOS 9.0.