I am developing an iOS app which needs to receive regular data from the server at specific period of time (every 5 seconds).
Apple gives developers some choices for background working.
I convinced that Background Fetch is the proper method for my problem.
But when I tested it I got confused.
Background Fetch has many issues with my requirements:
It does not fetch data at period you defined when declared it:
application.setMinimumBackgroundFetchInterval(UIApplicationBackgroundFetchIntervalMinimum)
I tried this and this:
application.setMinimumBackgroundFetchInterval(5). But no guarantee
that your app will fetch data at this interval.
When the screen is off, your app will not make any fetch until the
phone is unlocked again.
I wonder if there is a way that let my app receives real time data (or at least every 5 seconds).
Note: I read about remote notifications and I do not guarantee that I can execute it now, So I am searching for other solutions.
Thanks
There is no solution to this problem until writing this answer.
If I need a real time notification then I must use Push Notification.
There is no way to check for server data every period of time from the app only, I can send a Remote Notification when new data available on server to wake up the app and let it connect to the server.
Related
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.
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 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/
I am new to IOS and wants to used Local Notification feature of iOS.
my problem is i do not know if i can go with local notification. in my case data will come from web service... it is like..no specific date. default time interval is 60 Sec. after 60 sec app has to call webservice which will return notification data..and after some validation i need to push to user.
and if user click on view details it will launch appand get data via webservice.
Is using localnotification will serve my purpose? or i have to go with other approach?
Please help.
Thanks in advanced.
I think this 60 second thing is you polling the server every 60 seconds to fetch new data, then if there is new data post a local notification?
This is kinda possible with iOS7 but not exactly every 60 seconds, sometimes not at all, But in general it is strongly frowned upon. Instead the webserver should send push notifications when new data is available, It saves the user battery life.
On iOS7 there are silent push notifications (just don't include the alert) that can ask the client to do the validation you mentioned, and If the user needs a notification you can create a Local Notification to alert the user in a change
You should give this documentation a long look, it isn't trivial work for a new iOS programmer:
https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/Introduction.html
And here is a relevant Apple documentation quote "Local and push notifications serve different design needs. A local notification is local to an application on an iPhone, iPad, or iPod touch. Push notifications—also known as remote notifications—arrive from outside a device. They originate on a remote server—the application’s provider—and are pushed to applications on devices (via the Apple Push Notification service) when there are messages to see or data to download."
If you are trying to achieve this functionality to happen automatically/polling (i.e without user interaction like, clicking on the view details button)- the answer is a big NO at least not till iOS6.x
Your application cannot run for infinite length in background at-not till ios6.x. You may have to consider using APNS service to achieve this.
Otherwise, your approach on scheduling a local notification for ever 60 sec - The user clicks in the view option - the application comes up - You make a web-service call - Get the data - Validate the received data - Uploading to the server, looks fine to happen.
Will it not be annoying to the user getting notification for ever 60 sec & operating on the app to do whatever you intended to do? - Just curious.
It's generally a common question.
I wonder how do mail apps implement functionality of email-receiving?
I need to implement a simple sync between two devices(for example) using my web service.
Imagine a to do list app.
Is it possible to implement such a functionality: device1 makes an entry,then sends a message to webservice, webservice informs device2 that changes took place and device2 adjusts its data and displays that entry?
On iOS what you want could easily be implement with push notifications.
As soon as the server detects changes that device2 needs to be aware of the server will send a push notification to that device.
After the user views the notification the app should update it self, it would also be a good idea to let the app update it self when coming to the foreground.
The reason for doing it with Push Notification and not polling is that if your app is in the background you can only continue to run a process for 10 min max. You might get around this by adding the background mode to your app, like VOIP, Audio or location. But if you app does not fall in those categories apple might reject your app.
With Push notification the device will receive the notification even if your app isn't running or in background.
Basically there are 2 ways:
polling, each device asks the webserver for changes every N minutes: new todo, delete a todo, change a todo, ... and then each device will adjust. The frequency of the poll depends of the level of real time you are looking for. It can be 1 call every second or every 12 hours or much more.
implement a kind of BOSH protocol: the device opens a connection to the server. The server keeps it open until there something new to send to the device or the connection times out. In that case, the device reopens it.
Option 1 is better for your todo app because you don't need real-time accuracy. The option 2 is better for a chat application where you don't want to wait for the message.