Apologizing in advance, I am no 802.11 expert and this is a long winded question...
I am working on an iOS voip client, we use the Cocoaasyncsocket library for our TCP/UDP connections. The app/iDevice is allowed to roam in/out of wifi coverage (for the purposes of this discussion we will assume the app is using wifi only... no cellular connection). We have the appropriate plist settings for backgroundmode (voip, audio) as well as requiring persistent wifi.
We are having a problem that seems particular to Cisco AP's. With the client app in the foreground and roaming out and in of wifi range, we noticed that eventually the iOS device will eventually not automatically rejoin the network. After a great deal of debug the failure to rejoin was noted to have nothing to do with the app. The failure to re-join can ultimately be reproduced by forcing the AP (via config) to deauthenticate the iDevice three times. After the 1st and 2nd deauthentications, the iDevice readily automatically re-joins. But after the 3rd time, iOS does not automatically rejoin the network.
The network will be rejoined if, for example, the iOS email app is put in the foreground.
We were curious if any other VOIP type apps suffered this problem, and ran an experiment with running FaceTime and Skype on the iOS device.
Skype behaved much like our voip app, after the 3rd deauth the connection was lost. Trying to initiate another call resulted in a message to the effect of "must have an internet connection to make a call".
FaceTime did disconnect on the 3rd deauth and failed to automatically rejoin... however, we were able to re-initiate another FaceTime call which caused iOS to rejoin the network and make the call.
We would like to emulate the FaceTime behavior, but so far do not understand what we should be doing differently. To the best of our knowledge, we are properly closing the open sockets when we get disconnected. Is anyone familiar with this issue and have some insight to offer?
Related
I have an issue in my app where if a client is running my app but does not have wifi enabled, the app does not find my service and returns an "Unknown error" CFNetServiceError code 72000. The client enables wifi, connects, and my app is clueless.
The obvious fix is to add a notification for when a local wifi network is connected and reinitiate the NSNetServiceBrowser's search.
I don't know how to do that in C, so I was hoping to use Reachability. To my dismay, the solution I seek has recently been removed.
This is from the Reachability ReadMe file.
Removal of reachabilityForLocalWiFi
Older versions of this sample included the method reachabilityForLocalWiFi. As originally designed, this method allowed
apps using Bonjour to check the status of "local only" Wi-Fi (Wi-Fi
without a connection to the larger internet) to determine whether or
not they should advertise or browse. However, the additional
peer-to-peer APIs that have since been added to iOS and OS X have
rendered it largely obsolete. Because of the narrow use case for this
API and the large potential for misuse, reachabilityForLocalWiFi has
been removed from Reachability.
Ok, fine. But what the hell are these additional APIs? I need a method. :(
I am using Multipeer Connectivity Framework in my APP and its working absolutely fine but when APP is invoking any API or downloading any file from server then its delaying the response. Sometimes its failed and sometimes I am getting Time out error.
I have also checked "Network" status on xCode debug navigator and found that speed is going up and down instantly and never going beyond 6kb/s and sometimes its showing as 0 kb/s but when I disable Multipeer Connectivity then it works fine and speed going at 70kb/s too.
I have also noticed that if bluetooth is ON then its happening not with the Wifi.
Any suggestion would be really appreciable.
This is happening because when advertising, Multipeer always advertises on the wifi (there's no way to say bluetooth only). The way it advertises is by switching the wifi access mode into adhoc multiple times per second to find other peers, then switching back to AP mode (ie. resuming its connection to your wifi router). Doing this is highly disruptive to large transfers.
You have two options to fix this:
1) as soon as you can, after getting connected, call stopAdvertising(). This will stop the wifi mode from being constantly changed, and your throughput will resume at its normal rate. Warning: you cannot micro-manage this, because it takes up to 30 seconds after calling stopAdvertising() until it takes effect
2) switch from Multipeer to an alternative framework that allows you to specify bluetooth-only, and only use bluetooth. I wrote one called BluePeer which I use in my apps. It is unicast (not multicast) and supports roles like Client/Server (as well as role-less like Multipeer)
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'm trying to build a hack so that I can echo incoming TCP packets to local UDP (to connect to 3rd party control surfaces that don't support TCP).
I don't care if Apple won't approve it, I only need to do this on my own iPads. I tried pretending that my app supported audio but that didn't work.
Is this posible (without jail breaking?)
I haven't actually tried this but you might be able to do it by setting the app up as a VoIP app.
From the developer documentation:
Rather than keep VoIP apps awake all the time, the system allows them to be suspended and provides facilities for monitoring their sockets for them. When incoming traffic is detected, the system wakes up the VoIP app and returns control of its sockets to it.
Is it possible to build a socket connection between 2 iOS devices connected to the same network (Without net)?
if it's possible .. Is (CocoaAsyncSocket project) useful for me?
I just want to send a message from Device A to Device B which put the app in background .. when Device B receive the message should show notification to return the app to foreground.
It's not for the App Store, so I don't care if Apple would reject the app because of this behavior.
Yes, you can do it, and yes, CocoaAsyncSocket would be useful. If you don't have to worry about the carrier network's firewalls and filters, then you should certainly be able to build a client-server app running on two iOS devices. One opens the server socket to listen, and the other one (the client) connects, via the Wi-Fi network.
Trying searching on Google (e.g. "CocoaAsyncSocket iPhone iOS site:stackoverflow.com") or directly here on Stack Overflow.
Here's somebody who seems to have accomplished this
Another link
And a post from Robbie Hanson himself, referring you to the EchoServer projects in the github repository
EchoServer project
You may have to use a static IP address for the server device (I'm not sure how much control you have over the Wi-Fi network's configuration), or use some other mechanism for letting the two devices discover each other.