When NEVPNProtocol property is updated by the server such that the username & password isn't valid anymore, is there a way we can handle this?
Lets say if we turn on onDemandEnabled flag for NEVPNManager, and when the server invalidates the credential (since the user has been blacklisted), is there a way we can toggle this programmatically? From the end user's experience perspective, the user would wait for a long time to fail webpage loading. Background fetch using a timer might not work if the app is killed.
Other than using push notifications, is there a better way to solve this issue?
I didn't try it myself, but what you should do is when you configure your VPN and set the onDemandEnabled, you need to define the onDemandRules.
There you have NEOnDemandRuleDisconnect, which will prevent your VPN from starting, and will disconnect it if it's already active.
https://developer.apple.com/library/ios/documentation/NetworkExtension/Reference/NEOnDemandRuleDisconnectClassRef/index.html#//apple_ref/occ/cl/NEOnDemandRuleDisconnect
This way even if your VPN is active, you will use it only when the rules still applies.
Edit: you can also use onDemandRule - probeURL . With this, before any activation of your VPN, it will send a request to a server of your choice. The server will return an answer if you should use your VPN or not.
Related
I'm trying to connect to our push server via MQTT-Client-Framework.
There is no complication for connecting to server and with a few line of code i can connect to server and subscribe to topic.
but I have a few question that I could not find any direct answer for them.
1) How can I keep my client running at background?
2) What happen after device restart? how can I automatically connect to server after device restart?
3)Suppose I got an error during connecting to server. Will this library trying to connect in a loop? how many times it try? or I need to manage this myself?
4) The same 3 scenario for subscribing to topic?
Based on my experience on MQTT-client framework following are the answers to your questions/queries. I hope it clarifies your concerns and helps you to move ahead.
1) How can I keep my client running at background?
You can not keep your MQTT client running in background, as Apple doesn't allow any application to keep running for long time in background. Though if you override its not guaranteed your application will keep running in background. You can read more about background execution support in apple documentation.
Also refer issue posted on github for given framework.
2) What happen after device restart? how can I automatically connect to server after device restart?
Each time your app begin execution you need to connect to your server using MQTT client framework there is no auto connect mechanism available in MQTT-client framework. I suggest to write init your connection in specific controller which executes immediately after your app launch except same as AppDelegate
3) Suppose I got an error during connecting to server. Will this library trying to connect in a loop? how many times it try? or I need to manage this myself?
If your MQTT-client fails to connect your server, you need to handle it yourself, library doesn't try to auto connect as mentioned in previous answer. I have written sample code as below. Use NSTimer for auto connect to server.
[self.mqttSession connectToHost:MQTT_HOST port:MQTT_PORT usingSSL:NO connectHandler:^(NSError *error)
{
if(error)
{
// Application fail to connect to server, write your code to auto connect here
}
}];
4) The same 3 scenario for subscribing to topic?
If your broker server has configuration to track your existing subscription for individual users/client then you don't need to subscribe each time.
Otherwise each time you need to subscribe to same topic on successful connection. Use following MQTTSessionDelegate method to subscribe.
- (void)connected:(MQTTSession *)session
Happy coding :)
1)Project->Capabilities->Background Modes. There has some options for allowing your app to run at background.
2)Generally speaking, MQTT will not be disconnected to the server if your app is allowed to run at background, but i think you would better check up the connection and maybe re-connect MQTT to your server when the app become active again.
AppDelegate-> - (void)applicationDidBecomeActive:(UIApplication *)application;
3)Unfortunately, yes, it will. And you have to manage yourself.
4)I can't help.
For your first question:
Details on how to run in the background on iOS can be found here. This link also lists the actions that Apple allows to run in the background, if your app does not meet those criteria then it is likely to get thrown out of the app store by Apple.
The list also shows which UIBackgroundModes to place in your Info.plist to flag that your app needs background access.
The other 3 I can't help with
We all know that Apple doesn't allow app service to run in the background, so MQTT will be disconnected in the background mode.
Now do one thing use better frameworks for MQTT like this in this framework you will get auto-reconnect and callbacks and many things.
So When you receive a call back that the MQTT is connected, immediately subscribe to all the topics that you have.
And if you want to get all missed messages then you need to change the MQTT configuration to like 'clean = false'.
I am trying to understand the best practice for remote notifications on iOS when the user has a particularly poor network connection or no network connection.
The scenario is such:
The user gets some remote notifications and at some point in the future opens the app. At this point I wan't to let the server know ASAP that the badge count is now zero. I am using server side badge count management as the only way you can update the icon badge reliably is in the APNS payload. However the call to the server fails as there is no network connectivity. Then the user puts the app into the background so I can't make any further calls to the server if network came back. Subsequently a new remote notification comes in but the badge number is wrong because the server doesn't know it needed to be zeroed.
Am I missing something here? Any advice gratefully received as I haven't found any articles online dealing with this scenario.
Yes, you have implemented in right way. We can't do anything if there is problem in internet connection. Badge count is managed by server only. So, whenever you open application, application will update Zero to server. Now, if it is not properly updated to server then it is not possible to manage it from Mobile side.
I see a lot of Reachability examples where people only display a message when reachability status changes.
But recently, I saw in Foursquare app that they display a message every time the user try to make an action requiring an Internet connection.
I think this is more robust and a better UX to remind the user he can't do anything without Internet. Mainly because users can switch between apps, do something else and forget he has no connection when he comes back.
Also as soon as they get the connection back I can see that they fetch data from the Internet and refresh the UI.
What I am really looking for is the best way to do this. How this is done?
Do they have a general UIViewController that checks for reachability each time it needs a connection?
Or do they have a kind of proxy class before each Internet request that cancels the request and display a message?
How you guys are dealing with that?
Thanks.
EDIT:
The solution I came up with is using AFNetworking which also provide reachability status in the box.
Basically I created an AFHTTPClient and set a reachability callback block on it to listen to status changes. The AFHTTPClient object is application wide (kind of a singleton). (in fact I have one AFHTTPClient per host I need to reach a.com, b.com ...).
Then when I need to perform a request I create a new AFHTTPRequestOperation (AFJSONRequestOperation in my case) and I enqueue it on my AFHTTPClient object.
In the failure block of the operation I check to see if the host is reachable with the networkReachabilityStatus property of the AFHTTPClient. If it's unreachable I display a message that there is no internet connection to the user.
I wrapped that up so I don't have to do this each time I create an operation. So now in the app, each time the user try to do something when there is no connection he got a message remembering him that he has no internet access.
I also use the reachability callback to reload data on a screen once I get the connection back (or rather once I am supposed to have a connection).
I don't know if it's best practice but I think it's nice to know that the app takes care of reloading important data as soon as a new connection is available.
If someone is interested by a sample code I can provide it.
On a WWDC talk this year the Apple engineer on stage recommended users to never base the application internet access on the Reachability example app status. Often reachability doesn't provide a complete information (it is based on a complex mechanism) and the suggestion provided by the engineer was this:
try to do your internet connection, whatever it is the Reachability status; then set your UI hint based on success/fail result
if it fails due to networking issue, then register to Reachability and retry again when Reachability gives the green light; this is needed when you want to recover automatically from the fail condition
in any case give the user the possibility to "force a retry", whatever is the Reachability status. If it succeeds, reset your UI hint immediately.
What the Apple engineer said is perfectly true: quite often you can see in the console log Reachability failure messages while the internet connection is perfectly alive.
Other thing: there is no better "network hint" than the one displayed in the status bar: if you have there the wi-fi icon, the 3G/4G icon, the cellular field strength.
Returning to your original question: there is no absolute better way to manage this stuff, this depends heavily on the application architecture. In case you prefer to concentrate your networking stuff in a dedicated class (not a UIViewController but a NSObject subclass) then it could make sense to define a read-only property for that class that is updated with "success/fail" after latest internet connection with the servers app (it makes no sense to ping other servers like Google or Apple: first of all it's not elegant, second the issue may come from your the servers that serve the app and not the device internet connection status!). #property (readonly) BOOL lastConnectionToMyServerSuccess
Then your view controllers can register (by KVO or by central notification) to this property changes and update their UI accordingly by showing an icon or else (I repeat: leave the user the possibility to try manually to connect to the internet). View controllers should unregister from KVO when out of sight ("viewWillDisappear:") or unloaded ("viewDidLoad:") or dealloc'd.
Of course this adds some extra complexities. E.g.: you use the app, the internet light was green. Then you suspend it, do something else and after a few minutes your return to the app. In such case the app should ping your servers to restore the internet light status again, as after a few minutes network conditions could have changed (e.g. you are on a train). In any case all loaded view controllers will get the KVO notification from the network dedicated class and update themselves.
I have an app that tracks wildlife where the user enters data based on their observations (eg. user enters they see 3 moose). The data is then uploaded to a server. However, because this app will be used out in the field where there is often no internet connection, I want to save data if there is no connection, and upload the data as soon as the network is available
I know about Reachability, but it looks like I can only check if the internet connection is available at that moment, and doesn't check in the background for internet connectivity
So to summarize:
If there is an internet connection when users submits data, then that's fine.
If there is no internet connection, when user submits data, I want to save this data. As soon as there is an internet connection, I want the data to be uploaded, without needing the user to open up the app again. I can't rely on the user to open the app again causing the data to be submitted, because they will likely only use this app out of the range of cell towers, and will likely NEVER run the app in a location with a network connection, so it would have to automatically submit this data for them.
Looking around, I can't find an answer so I'm beginning to wonder...is this even possible?
No, Apple don't allow applications to run indefinitely in the background for this purpose, and they don't allow applications to be triggered remotely or anything of that nature. At best you could have your application run in the background to get notifications about major location changes, but you'd have to have it as a proper feature rather than a hack to get around this limitation, otherwise your application won't get approved by Apple.
I know it's possible to utilize the network in the background but only for a limited time after the user closes the app. You could create a timer which checks for a network connection (using Reachability or by pinging Google) and set the timer to fire every minute after the app closes. It's not a very efficient solution but it may work. You should look into how long you can maintain a connection after the app close though, I think it is 5-10 minutes.
I am working on a web application for iOS that is going to be accesed from a local webserver in a network that has NO internet connectivity at all.
My problem is that everytime an iOS device is locked, it disconnects from the WiFi network, so when the device is unlocked again, it has to reconnect. Part of that reconnection process is determining if there is Internet connection (which there isn't). Until the process is not finished iOS does not allow any DNS resolution (so if I write http://10.0.0.1 it will go there, but not if I request http://something.local.com).
Since we control that network, we want to know how to does iOS verifies Internet connectivity so that we can fake the responses it expects.
I don't know if it's possible to resolve DNS without an internet connection on iOS, but if that's the case, that would be a way better solution since you don't need to mess with your router settings. Use my solution only if it really isn't possible with only code.
I'll suggest you to follow this guide: http://blog.jerodsanto.net/2009/06/sniff-your-iphones-network-traffic to check which actions your iPhone executes to detect an internet connection.
Using this information you could forward the is-there-internet-requests on your router to a local server which fakes the there-is-internet-responses.
This assumes Apple really uses an external server to detect this, which I'm not sure about. But it wouldn't hurt to give it a try!
Have you looked at the Reachability Class? You don't have to use the reachabilityForInternetConnection method, which checks if a default route is available. You can use the reachabilityWithAddress: method and check if your server is reachable.