Was reading through the iOS4 documentation for multitasking, and couldn't figure it out.
I basically need to update the badge count on my app's icon after midnight each day as long as the app is running in suspended mode (with multitasking).
I know this has to be possible, just can't figure out the best way to do it.
Thanks.
iOS "multitasking" is very specific. There's an important distinction between states here:
Suspended: Your app resides in memory, but does not receive any execution time. This is really only useful for fast app switching.
Background: In a few particular cases, you can request that the OS to run your app in the background. (Playing audio, location, finishing a long task, voip.)
So, the short answer to your question is, "you can't."
Here are a couple useful links on iOS multitasking, such as it is.
Understand an Application's States and Transitions
Executing Code in the Background
You could use a UILocalNotification to set the badge (without an alert) but you can't increment the badge because you're app does not have the opportunity to execute any code when the notification fires.
You can schedule up to 64 notifications in advance, one at midnight for the next 64 days, each one setting a new badge number. It would make a lot more sense to schedule a repeating notification but since your app can't execute code it can't increment the badge number that doesn't work.
Related
I've read several posts on creating a timer that runs in the background. Is it possible to create a scheduled timer that will continue to run once the app has been suspended/terminated?
Apple's own timer achieves this, but it's not clear how. I am guessing they send a local notification for the timer expiry, and maybe they undertake a date object comparison if the app is brought to the foreground while still in the countdown period. Is this a correct assumption? Any pointers would be helpful.
In short, what you're looking to do is not possible - since the amount of time your app is allowed to run in the background is limited to ~3 minutes. Look at this answer for more details.
You could achieve your goal through the use of a push notification, but that would require a server and won't guarantee it is received at the perfect time.
You might also want to look at this question
It also appears based on this answer that you cannot set a timer in the standard clock app either.
TLDR - You can't create a timer app.
I have an iphone app that has a 30second process that does some network IO. Basically, while the app is in the background, i want this process to run every hour (actually once a day, but if it fails i want it to re-run in an hours time).
With the background features of ios 4, is this possible? If so, how? What are the limitations that i'll come up against?
Thanks so much!
Take a look at Apple's documentation about running code in the background.
http://developer.apple.com/library/ios/#documentation/iphone/conceptual/iphoneosprogrammingguide/BackgroundExecution/BackgroundExecution.html
There are few different ways of approaching backgrounded tasks. The only apps that can have fully backgrounded processes are "audio", "voip" and "location" apps, and this needs to be declared in the Info.plist.
If your app is not of this type, you'll probably find it difficult to do what you want easily. There are methods which allow you to keep your app alive in the background for a finite period of time (also at that link), but eventually your app will be shut down.
Local Notifications will only prompt the user to open the app - do you really want to have an alert pop-up on the phone every 30 seconds?
I was making some kind of similar research, have a look at this SO answer in case you didn't manage to find it before. Applications like DataMan or Data Usage must have some sort of periodic code execution in the background, so I'm not 100% convinced that what you're asking for is impossible..
I believe that Using Local notifications will help....
check following....
http://developer.apple.com/library/ios/#documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/IPhoneOSClientImp/IPhoneOSClientImp.html#//apple_ref/doc/uid/TP40008194-CH103-SW1
An application can create and schedule a local notification, and the operating system then delivers it at the schedule date and time. If it delivers it when the application is not active in the foreground, it displays an alert, badges the application icon, or plays a sound—whatever is specified in the UILocalNotification object. If the application is running in the foreground, there is no alert, badging, or sound; instead, the application:didReceiveLocalNotification: method is called if the delegate implements it.
The delegate can inspect the properties of the notification and, if the notification includes custom data in its userInfo dictionary, it can access that data and process it accordingly. On the other hand, if the local notification only badges the application icon, and the user in response launches the application, the application:didFinishLaunchingWithOptions: method is invoked, but no UILocalNotification object is included in the options dictionary.
I'm working on an alarm/reminder application and want to show a custom alarm view when specified time is reached.
From what I understand, there are various (real and hypothetic) ways of doing it:
UILocalNotification. It would be perfect, but alert customization features are insufficient, e.g. I can't show a custom alert view, I can't play a sound for more than 30sec etc.
Keep application in the background and use NSTimer or other means to schedule execution after some time. Most likely won't work as the app may be killed any time.
Start my app at specified time to receive the notification. As far as I know it's not allowed at all.
After spending several days searching for a solution, I would give up and stick with UILocalNotification, but I DO know an app that shows custom alert view at specific time AND is available in AppStore. The app is named "Alarmed" and from what it looks like (last app view shown on alarm time before an actual alert; alarm still triggers even after the device is restarted) they found a way to start their app at specific time and still pass Apple's review.
Any ideas how this can be done?
Thanks.
It's not possible to show notifications other than what UILocalNotification offers you, unless the app is running in the foreground. (I just tried to install "Alarmed" and it uses a regular UILocalNotification like you'd expect).
Is it possible to have an App (running iOS4 on hardware supporting multi-tasking) which starts on iPhone startup and then regularly checks for online updates (every 15 minutes) and then refresh the badge, so the user can see how many unread items there are with-out having a push-server?
I was hoping this would be possible with iOS4 Programming Guide seems to suggest it is only possible to to this regarding Locations tracking, VoIP and playing background audio. There is also the possibility to do local-push notifications, but I don't see to find how to trigger a specific function that way.
Thanks in advance for any help!
edit:
Just having read a bit more, if the application is in the background/inactive state, and I son want to update the badge-number without displaying a message, is there an action triggered like didReceiveLocalNotification? There must be a way to schedule something on a regular basis (like email checking) without having to implement a full server-push-nitification system!
Is it possible to have an App ... which starts on iPhone startup and then regularly checks for online updates (every 15 minutes) and then refresh the badge
As you already figured out, the answer is no.
Let me rephrase to make it clearer:
How can I have an "alarm" go off 20 minutes after my app has gone in the background?
Old question:
How can you have the simplest tast happen after 5-10-60 minutes on iOS? Essentially, have an NSTimer fire after a predefined interval.
I do "begin task", sleep( for some time ); and then "end task". However my app usually gets killed if I sleep for more than 5 minutes. I've seen posts around that mention that apps can stay alive in the background for a few hours, how exactly can that be achieved?
When your app goes to the background, the system will try to recollect as many as resources as you can give it to him like Images, nibs, etc. You have a notification for this. (– applicationDidEnterBackground:, etc)
After that, it will "sort" all the background living apps according the resources usage order. The app that uses more resources comes first.
Then when a new app comes to the foreground if the systems thinks it needs more resources than it currently has it will start killing background apps. using the above sorted list.
This means that the less resources you use in the background, the longer your app will live. BUT, there is no guarantee it will live long. (Everything depends on user usage). There is also no notification when it gets killed!, so you cannot assume your app will live for 60 min.
You probably want to read this Apple doc on how to do something in the background (with some time restrictions, off-course) and probably also UIApplicationDelegate class reference.
Hope it helps ;)
Just use a local notification