I want to send UDP packages in a local network using GCDAsyncUdpSocket.
My fear is that at some point UDP packages will be sent via LTE because of the newly introduced "WiFi assist" from iOS 9.
Is there some way I can pretend iOS 9 from passing my traffic to cellular network, and instead require it to always use WiFi?
Thanks a lot for any ideas!
I think you can use "Reachability" to detect if the phone is connected to a wi-fi or to cellular data and then avoid to send message or manage the that particular condition. You can also ask to the user to disable the wi-fi assistant with a popup just to be sure to avoi the problem.
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I want to create an iOS app to connect my Wifi OBD 2 to the iPhone. But i have no idea on how to do the peer connection with swift 2. I have the OBD doc to communicate with it (https://www.elmelectronics.com/wp-content/uploads/2016/07/ELM327DS.pdf - page 30).
I tried to search the same thing on android and windows but the problem is my knowledge on peer to peer iOS communication.
I see a lot of iOS app for OBD protocol on app store, I'm sure that anybody can help me !
Thank you !
You don't need to know about real wifi peer2peer communication. Once you attached your phone to the wifi network created by the obd2 wifi adapter, you will be able to establish a good old TCP-connection to it. By default most wifi adapters listen at 192.168.0.10:35000 for incoming connections.
After establishing the TCP connection you can communicate via AT and PIDs by writing/reading to/from the socket. The actual protocol is described in ELM327 manual and the ISO/SAE standard documents.
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?
iOS 7 introduced a new user configuration to disable cellular data for specific apps. It can be configured in "Settings"->"Cellular" and then scrolling down.
You'll find a switch for each installed app and can see how much cellular data it has consumed.
How can I programmatically test if the switch is turned on for my app? Is there an API for that? Can I determine how much data my app has used over cellular?
I'm not asking to get the values for all apps. I'm only interested in my apps usage.
There is no API to detect your download consumption or whether cellular is active for your app.
If your app tries to connect to a website, but cellular is turned off, then iOS may ask the user to turn cellular back on. I'm not exactly sure how that works, but it is probably similar to the iOS 6 "no network connection" alert that would pop up if there is no connection but an app tries to access the internet.
You can check if the current internet connection is over WiFi or Cellular, but if Cellular is disabled you will just be told that there is no network connection.
More details here: iOS Detect 3G or WiFi
You can't check if the cellular data switch is turned on.
The closest thing is that you can check if a specific host is reachable over cellular connection using the SCNetworkReachability kSCNetworkReachabilityFlagsIsWWAN flag.
Additionally, you can enable/disable cellular data for specific connections using the NSURLRequest allowsCellularAccess property.
Reference: https://developer.apple.com/library/ios/documentation/NetworkingInternetWeb/Conceptual/NetworkingOverview/Platform-SpecificNetworkingTechnologies/Platform-SpecificNetworkingTechnologies.html
This answer suggests how data usage can be measured system-wide: iPhone Data Usage Tracking/Monitoring
I want to use a messaging protocol that works fine over 3G, but not over some corporate firewalls. How can my app force the use of the cellular network when it fails to connect over WiFi even in the case that the WiFi network is reachable?
EDIT: After reading through the implementation of the Reachability class I remain unsure whether the two are indeed mutually exclusive. It could well be possible to discover both interfaces via gethostbyname(), which I might try just to see what comes out.
Use getifaddrs to enumerate the network interfaces. Look for ifa_name that starts with "pdp." This will be the cellular interface (e.g., pdp_ip0). Test (ifa_flags & IFF_UP) to make sure the interface is up, and get the IP address from ifa_addr. Then use bind() to bind your socket to that address.
Not sure how you activate the cellular interface if it is not already up. Normally, I just make a high level http call to get iOS to wake up the network, but not sure under what conditions the cellular service becomes active when wifi is also available. I suspect it is usually there as a fallback to the wifi.
http://iphonedevsdk.com/discussion/comment/120957
From the looks of that thread, it seems like its impossible. Your best bet may be to try using the protocol, and saying something like "please disconnect from wifi and retry" if it doesn't work.
This thread says just about the same thing:
how to programatically start 3g connection on iphone?
You can use the Reachability class which apple wrote in order to test whether the network connection is currently over 3G or WiFi, and even to check if a specific resource is available on the network.
You can use any of the socket library to force to use cellular. Find the cellular interface from getifaddrs, pass the interface to the socket function, socket bind will happen with cellular. e.g. CocoaAsyncSocket
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.