I was wondering how some existing apps refresh their application data while the app isn't running. Lets say we have a rain alarm application. This application send you a (local?) notification when its about to rain in your current location or location you've manually entered. What's the best way to achieve something like this?
Is the application getting weather data on the device itself (even when the application is killed) to send a local notification when its about to rain? Doesn't this method drains the battery of my device?
Or do I need to create a standalone application which runs 24/7 and always checks the weather? It then searches a database to see who's device needs a remote notification.
Other methods are also appreciated.
In iOS6 and before, your app cannot run all the time you want in the background, the system will stop the app after a few seconds.
A way that your example can be achieved is sending push notifications from a remote server.
Note: In iOS7 it will be possible to wake you app when a notification is received and download content.
Related
I have a chat application, developed on the Xamarin.Forms platform, in which users can chat with each other. I have managed c# code and UI both in the shared project.
I have been facing problem since long in iOS platform. When the iOS app is running on screen, having foreground mode then the app can successfully receive a message which has been send by another user. When the app is running in the background mode and someone sends a message, I want to notify the user by using local notification (No Push remote notification - Because I think as my app is already running in minimized mode there is no need to wake up the app by implementing Push notification). Even I have implemented local notification successfully but the problem is,
When the iOS application heads to the background mode, the main thread (task) is paused so, when some user sends a message the app is not able to execute the code (when app is minimized) so that it won’t be able to show the local notification. But when the application is brought back to the foreground the thread/task get resumed and then ie shows up the local notification and also the message.
I already have selected the "Background fetch" property under Background Modes in Info.plist. I have also added below the line in my FinishedLaunching method
UIApplication.SharedApplication.SetMinimumBackgroundFetchInterval(UIApplication.BackgroundFetchIntervalMinimum);
I have already worked and implemented code from below links, but didn’t worked for me.
https://learn.microsoft.com/en-us/xamarin/ios/app-fundamentals/backgrounding/ios-backgrounding-techniques/
https://learn.microsoft.com/en-us/xamarin/ios/app-fundamentals/backgrounding/ios-backgrounding-techniques/ios-backgrounding-with-tasks#performing-tasks-during-didenterbackground
Xamarin forms background tasks run only when app is open on ios
https://arteksoftware.com/backgrounding-with-xamarin-forms/
When an iOS application goes to the background, are lengthy tasks paused?
How to perform a simple background task on Xamarin iOS
https://learn.microsoft.com/en-us/xamarin/ios/app-fundamentals/backgrounding/ios-backgrounding-techniques/ios-backgrounding-with-tasks#creating-background-safe-tasks
https://learn.microsoft.com/en-us/xamarin/ios/app-fundamentals/backgrounding/
I think my issue is relate to iOS Background processing, So, does anyone has idea what to do, to execute the code when app is already in minimized mode?
Generally speaking, backgrounding is very restricted on iOS. If your app is in a certain category (e.g. Navigation, Music) you'd get extended backgrounding capabilities, but I don't believe that chat apps do. More specifically, Background Fetch is not really suitable for your problem. It is called on an irregular basis to fetch contents to be cached within your app in order to make showing contents to your users faster. Background fetch intervals may vary from 15 min to several hours (not sure about the latter).
What you need is remote notifications.
Remote notifications (also known as push notifications) let you push small amounts of data to devices on which your app is installed, even when your app isn't running.
Remote notifications are brokered via a priviliged service (Apple Push Notification service - APNs) to Apple devices and delivered in a timely manner (seconds rather than minutes or hours). Usually you'd want to keep the payload as little as possible (just send the chat ID for example) and let the app fetch its data when it's notified.
Speaking in terms of a chat application, your chat server would send the remote notification to the APNs whenever a user sends a message to the chat. The app would be notified, fetch additional data and then display the notification to the user. If the notification is tapped, the user would be taken to the chat window for the respective chat.
Please note that your app has to be registered with APNs, otherwise remote notifications won't work.
I am building an iOS application in SWIFT where user location is fetched and sent to the server after every 30 mins. When the app is opened it keeps sending the location lat/long to the server but when the app is closed or suspended it won't send. I want to send the location even the app is closed. Is this somehow possible? I just want to send the location to server no need to open the app again and again?
You app needs to support Background Tasks for being able to run in background.
I believe this has been answered multiple times. Here is the documentation link
Since you are using location, I would recommend you to use UIBackgroundModes as locations.But be sure you don't drain the users battery.
Also usage of background fetch (UIBackgroundModes - fetch) and silent notification can be a great way to get you app running after equal interval of time.
Update
For performing operations you can use silent notification - refer this apple documentation
As per documentation - the system wakes your app in the background and calls the application(_:didReceiveRemoteNotification:fetchCompletionHandler:)
Update 2
For local notification along with scheduling custom action refer this apple documentation. But I really doubt this will help you achieve your desired result. Mainly because you app would get an event only when the user performs any action on your local notification and if he ignores it, you app will remain in background.
I'm just wondering if using Local Notification is possible for my app instead of Push Notification.
My app get data from my sever via the server's API. It's a small social network for soccer player. I'd like the app to notify the user when the user's friends post a pickup game in the user's city.
Is it possible for the app to run a background process to poll the server for new pickup game in the city say every 10-15 minute, when there is a new pickup game, it sends a notification to the device?
What you want to do is implement the iOS7 background multi-tasking API and perform background fetches. Decent tutorial here: http://hayageek.com/ios-background-fetch/
You don't have control over when the operating system allows you to wake up in the background to perform the fetch, but during this operation you could poll your server and if new data was present use that to show a local notification.
It is not possible in the way that you're thinking. When a local notification is fired, you cannot execute any custom code unless (or until) your app is actually active. If the user does indeed tap on your notification in notification center, you can get the notification info from your application delegate from either the launch options in application:didFinishLaunchingWithOptions: if your app is starting up or from application:didReceiveLocalNotification: if your app was already running but in the background.
If you're okay with this only working while the app is actually in the foreground, then you can set whatever timers or notifications you want.
is it possible to have the App Connection to a server Open even if the App has been Terminated from the Background ?
Here is what I'm trying to accomplish
Twitter Client should keep watching user events . and when that events occur it send a Local notification to the user . the whole idea is to stay a way from Push notification and all servers Problems and costs
so in order to to get Local notification works just like Push notification the connection between my IOS 7 App and Twitter API must be Open all the time
any idea if that even possible ?
No, this is not possible. What you're basically asking for is a daemon functionality which is not available on iOS. The whole point about iOS multitasking is that the OS can (and will) terminate your app if it is in the background and other tasks need the resources. That's the problem Push Notifications solve (to some degree).
You could possibly try background fetch feature on iOS 7 to periodically download content updates for user in background.
In my app, I want to check my database every 12 hours for an entry and if found, set a notification.In android,it is accomplished by using a service.But in ios services are not allowed.I tried to implement NSTimer,but it will be reset when the app goes to background.I want my service to be run when the app is on background. On research the only possible way I found is to use push notification.But if the network is disconnected,push notification will not work and notification will not be set that day.Is there any other possible way to implement my requirement please?
Long-running background processes are only allowed for VOIP applications that need to maintain an open connection to a server.
Push notifications are not guaranteed to be delivered, however, if your server sends your iOS device a push notification, the notification will be queued at the APNS server residing at Apple. When the target device is reconnected to APNS, the notification will be delivered.
The only way you can check the database is when your app is running. You can't do it when your app is on background.
Only VOIP, Music and Location based applications can run on background for long durations.
You can use UILocalNotification to alert the user to open your app.