I am looking for solution to get data in background mode even app is terminated.
There are lots of tutorials and answers available for this questions, but my questions is different than other. I haven't find any proper solution on stackoverflow, so posted this question.
I have scenario which I can explain. I'm using realm database which store event date, name, time, address etc. Now the thing is that, I want to write a code which are execute in background, In this code I want to get all event data and compare their date with today's date. And based on days remaining between these days fire local notification to remind user about how many days are remaining for specific event.
I want to call this background fetch method exactly 8 AM in local time everyday.
I haven't write any code due to confused with Background fetch and implementation. Can anyone know how to implement this ?
Help will be appreciated.
I have got solution to fix issue. As per I have talked,
I want to write a code which are execute in background, In this code I
want to get all event data and compare their date with today's date.
And based on days remaining between these days fire local notification
to remind user about how many days are remaining for specific event.
So, when I getting response from API, I'm creating local notification for all events with unique id, which are fire and repeat daily at specific time, where I have display event time and remaining days of event.
Apple documentation states that there is no guarantee when background fetch is performed. It's up to the system to decide.
The system waits until network and power conditions are good, so you should be able to retrieve adequate amounts of data quickly.
The guaranteed way to wake your app is to send at 8 am VoIP push notification from the server. It is guaranteed that the app will be wakened upon receiving a push, and you'll be able to execute the jobs you need. For more details, https://medium.com/ios-expert-series-or-interview-series/voip-push-notifications-using-ios-pushkit-5bc4a8f4d587
It is not possible to wake up the app from suspended mode in iOS except with push notification (for this server has to send push notification).
This is something which is not documented anywhere. IMHO and experience with iOS, Apple must be recording user activities since the start of the iOS era. ScreenTime is a product of those recordings only that apple was able to create and visualize the data to present a user facing app that very beautifully restricts, manages and displays your activities. In WWDC 2018, it was even quoted that apple will even detect, if the user opens your app at let's say 9 PM daily before going to bed, iOS will allow every possible resource (battery, internet, processing time etc) to that app at 9 PM. But you need to understand your user activities before you do this. Let's take an example of:
News App:
A majority of users would check the news in the morning (If they are not instagram addicts). At this time even apple should be biased to open your app with background fetch. Unless of-course there is too much of a resource crunch
A Game: Many games allow provide a restriction time by calling it "recharge" or "re-fill" the energy of a character before user can play another round. This is done so that the addicted person would buy gems to remove that restriction and hence monetize the idea. But if you know that the refill process is completed before 8:00 AM in the morning or user plays your game daily at 8:00 AM configure background fetch accordingly.
Background fetch works with interval rather than specific time.
// Fetch data once an hour.
UIApplication.shared.setMinimumBackgroundFetchInterval(3600)
Lastly why don't you try silent push notifications? Based on your question, I think silent notification is enough to wake your app after a push notification from the server, download some data and do your calculation and provide a local notification.
Related
I am building a travel app which gives complete information about all transportation systems in my city. There is a requirement to notify the user when there is any change in time table of public transport/delay/any incident. To get that information, app has to hit the server at a specified time, say 9am everyday, and if anything is reported, that has to be notified to the user using local notification.
I am aware that this is not a proper design and there are many limitations with respect to Application states to fire the event. But still can iOS app manage such situation(which should work even when app is in background, suspended, inactive, terminated), as I am not getting any support from backend team?
Unfortunately if your backend team is not giving you any support then you are out of luck. Silent push is the only way to do this as per your requirement (exact time every day even if terminated). You could try the background update method, as apparently iOS learns when you're most likely to use a particular app and will schedule the update accordingly.
I'm trying to code an app that reminds me to hit a certain diet goal (drink 8 glasses of water, eat two fruits, take vitamins etc)
The problem is if I code these as reminders using local notifications, I don't get to execute code. So I can't adjust the reminders every hour relative to my goal. For example don't show the reminder if I already hit the goal. Or say stop the reminder past dinner time and start again in the morning.
If I code these as NSTimer the problem is they don't run in the background.
I suppose I can move all the logic to a server and use push notification instead. But this is huge amount of work for what I would consider a very simple self reminder app.
What is the right approach?
if I code these as reminders using local notifications, I don't get to execute code
I use a pill-taking app, and it does use local notifications. The local notification does let the app execute code, if the user taps / swipes (whatever) the notification. The app then puts up a dialog where I enter what actually happened (I took the pill, I skipped it, etc.).
The app simply assumes that if the user doesn't respond and tell it what happened, then nothing happened (i.e. the user missed the pill). How does it know that? Well, as with any local notification-based timer app, the app must maintain an internal list of pending events. It strikes a pending event from the list when it knows the outcome. That way, if the app is not running and then it is running, it can look back over its list and note that there are past pending events, thus proving that the user failed to respond to a reminder.
May be I am asking a stupid question here.
I recently noticed an UIApplication delegate method
- (void)applicationSignificantTimeChange:(UIApplication *)application {
}
I was wondering what will be its actual use? Do we need to handle this. Can anyone explain a scenario that can happen in an iOS application and we need to do some coding here.
My App is really sensitive to system time, that is the reason I am asking this question. After seeing this API , I have a feeling that I am missing something here to handle.
I am just curious to know... :)
Thanks,
Ramesh Chandran A
Per the documentation on iOS, this method is called:
Examples of significant time changes include the arrival of midnight,
an update of the time by a carrier, and the change to daylight savings
time. The delegate can implement this method to adjust any object of
the app that displays time or is sensitive to time changes. Prior to
calling this method, the app also posts a
UIApplicationSignificantTimeChange notification to give interested
objects a chance to respond to the change. If your app is currently
suspended, this message is queued until your app returns to the
foreground, at which point it is delivered. If multiple time changes
occur, only the most recent one is delivered.
Examples of when this should be used include:
If your app has repeating scheduled events, such as a local notification that now is past, and your app should reschedule the next notification (like daily reminders).
If your app displays data in time ago that needs to be correct, even if the user sets a bad time (for example a medical app that shows your current glucose reading or similar). If a glucose monitor showed an old glucose value as the users current glucose value for instance, the user could make the wrong decision and get hurt.
How you respond to this event depends on your application. You could for instance, read UTC from a server to see if the phone's UTC is correct within some margin, and take appropriate action, such as warning the user, or updating an internal offset between actual UTC and phone UTC.
Hope that helps.
-applicationSignificantTimeChange: is roughly equivalent to the UIApplicationSignificantTimeChangeNotification notification.
I have a custom date picker control that highlights the today date. Subscribing to this notification allows it to change its highlight at midnight, or if the user messes with the time setting manually.
I am looking on some way to notify users with a custom message every 8 AM every day.
I need to do some data processing before I display the notification(Get the number of patients for the past 24 hours) and notify the user about the data I got using some sort of notification.
I tried to create a local notification that fires every 8 am in the morning and that is working except It is requiring me to specify it's alert message and alert body at the time of it's creation instead of on before alert show.
I am considering push notifications but I am not sure how complex this may be.
How can I accomplish that?
A hack around can be to request background fetch time from the OS. You can reschedule the notification every time the background time is allotted to you with the current number of patients in the last 24 hrs. Just compute it every time the system gives you background time.
See this article for scheduling background fetch time
You can't do what you're asking with local notifications. They 100% require static content up front. You'll need to use push notifications to do this dynamically.
I'm doing an app that requires to reschedule local notification on daily basis. I'm aware about the repeatInterval property, but repetitioon here is like each 2 days etc.
I've seen silent notifications, but they can be used only with push notifications and due to some requirements I can't use that approach.
Now the app works on the hypothesis that the user will open the app quite enough to reschedule those notifications. This hypothesis is fine and we all agree that will work, but I will be more confident, if it would be possible to reschedule them on daily basis without opening the app.
I've seen the new API Background Fetch, this could be really good for me, but from doc and WWDC videos I didn't understand if it is possible to use for "everything" or just to fetch remote data.
As I understand you can do everything that does not take too long, plus you don't get a guaranteed interval when you app will be woken up - you just can request a certain minimum wake interval, which will be treated as a suggestion by iOS.
The only catch is that apparently you have to create an NSURLSession and actually do a web request, upon which return you can do whatever you want. So, you can do a dummy request and forget about any data you get returned, or maybe even create a failing request, as you are not interested in any real request at all - although I'm not sure what Apple will do when you implement the latter ...
You can use repeatInterval property of localNotification
localNotification.repeatInterval=NSWeekCalendarUnit;
For daily basis you can use NSDayCalendarUnit
No there are not API which can wake app after some time interval.
In back ground fetch mode application will wake up after you set minimum time. Application will wake up any time after minimum time interval might be after 5 min or 1 sec. and that will decide system on application usage. so we can not take this approach, if you willing to retrieve remote data compulsory after some time interval.this may help u.
http://www.doubleencore.com/2013/09/ios-7-background-fetch/