I am currently developing an app that will need to terminate after running in the background for more than five minutes. In order to do this, I will have to have a timer running in the background after the the Home button has been pressed or in case of an interruptions such as an SMS or a telephone call, then, after five minutes the applicationWillTerminate method will be called. My first question is should I put the applicationWillTerminate in the applicationWillResignActive method or in the applicationDidEnterBackground method? My second question is since this is an app with more that one view, Should I write these things in the AppDelegate class or elsewhere? Thank you for your response.
1) You can't force your app to finish programatically.
2) You should never call these AppDelegate methods by yourself. They're meant to be called only by the system.
Reference: UIApplicationDelegate Protocol Reference.
This is pretty ghetto, but what you can do is make your app crash when you want it to exit, and it will close automatically, granted that's not closing the app, but there's no real harm in it as long as you are in control of how it crashes try to go for a bad access error, aka trying to access something that has been deallocated
as for running a timer in the background, i don't know per say if you can do that, but as an alternative you can save the time when they leave the app aka the app goes into the background and then you can have all the events return to your app of the view controller that is first responder, and each UIEvent has a time stamp, and regardless of which event it is you can compare the time stamps and see if it's greater than 5 minutes
Regardless i don't suggest any of the above, but that is the best answer i can come up with for your question
the code for receiving events out side of your app
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
will start the event tracking and the call back is:
- (void)remoteControlReceivedWithEvent:(UIEvent *)event { }
but you have to remember to
[self becomeFirstResponder];
this tells the device which view controller to go to for the event tracking, oh and don't forget to resign first responder, and endReceivingRemotecontrolEvents
Related
When I open the app it fires the events viewDidLoad and viewDidAppear form my View Controller but when I close it and run it again it does not call any of them.
Any idea?
You need to read up on application states. Here is a link I found online outlining the different states:
http://www.techrepublic.com/blog/software-engineer/understand-the-states-and-transitions-of-an-ios-app/
What you really want is to be notified when your app becomes active.
Probably the easiest way is to implement the function applicationDidBecomeActive() in your app delegate. That will be called when your app becomes active as the foreground app either on launch, or when it returns to the foreground as the active app.
Note that if you want that notification sent to some object other than the app delegate you can listen for the UIApplicationDidBecomeActive notification.
currently I am testing AppDelegate methods, when they are executed by adding NSLog to every method. What is not clear to me is when method applicationWillTerminate is executed? I've tried to put app in background, then to terminate it, but log from Terminate method is not executed. What is executed is this:
2015-09-01 16:24:01.512 TestQuestions[2351:110179] didFinisLaunching
2015-09-01 16:24:02.530 TestQuestions[2351:110179] didBecomeActive
2015-09-01 16:24:05.864 TestQuestions[2351:110179] willResign
2015-09-01 16:24:06.322 TestQuestions[2351:110179] didEnterBackground
What is not clear to me is when method applicationWillTerminate is executed
Almost never. It can be called under certain rare circumstances where you are e.g. playing music in the background and are terminated from there. But in general you should expect that it will never be called, because by the time you are terminated, you are already suspended and your code is no longer running (and the system is not going to wake you up just to tell you it's killing you in the background).
One time that applicationWillTerminate will execute is when a user touches (once or twice) the Home button and then slides the app off the screen.
Personally I do this regularly since I touch the Home button to switch between regularly used apps that I want to make active, rather that finding them in my 9 pages of icons.
I'm doing an alarm application with repeat interval. My problem is that even if the user clicks the local notification, returns to the app, and then goes back to the home screen of the phone the UILocalNotification stills fire every minute. I'm aware of [[UIApplication sharedApplication] cancelAllLocalNotifications]; and I put it in the my viewDidLoad method. Any advice how I can fix this?
Putting it in viewDidLoad is good for some circumstances just not yours. Think about when viewDidLoad is called:
Called after the controller's view is loaded into memory.
So in other words, the next time it gets called is after your little ARC friend deallocates it from memory. So, yes, eventually cancelAllLocalNotifications will get called again, just not when a user puts the app in the background and then returns it to foreground, because its still has a home in memory; it will be called next time that particular view gets loaded into the memory.
Additionally, that probably is not good logic, because that will happen for every user, even if they didn't want to cancel the repeats.
Ultimately, you will have to create additional logic to decipher which users have, say, hit 'snooze' or 'cancel' with whatever resource works for you and your project. Personally, I would guide you towards using a category based notification, that way you cancel it as needed, instead of 'just in case'. See here how to set those up.
I've come across a strange error while programming my iPhone application. Basically when I leave my application in the background and then access it after a long time (i.e. the entire night while I'm sleeping), the viewDidLoad method seems to be called again even though I did not exit the app (I only double tapped the Home button or I tapped the Home button once) but still left the app in the background. However, if I leave the app on for a short period of time (anytime between a few minutes to a few hours), the viewDidLoad method is not called again and everything is as it should be. After doing some research, I found that it is because the viewDidUnload method is called (after the OS finds that the app is suspended for a long time), which calls viewDidLoad again when we bring the app back up. I found this out through this link: view seems to reload itself but it doesn't seem that there's a way to prevent viewDidLoad from being called when the viewDidUnload is called. Is there any way to prevent this viewDidUnload method from being called again? The thing is I want my app to be running for a long time in the background (i.e. a few days in the background) to collect data. Or, is there no way around this? Any help would be appreciated. Thanks!
EDIT: I have realized that after iOS 5, viewDidUnload is deprecated but this phenomenon still occurs. Any ideas on how to fix it? Thanks!
If you want to do stuff in the background you should look into background tasks.
Imagine the app is running and you press the iphone button (the phone button) and you exit the app. then you tap on the app again to enter the app. My problem is that when ever the user does this I want the viewWillAppear or viewDidAppear functions to be called, but unfortunately none of these functions gets called.
I want to know if these function won't get called, then what is the function that is called when the app is appearing again?
How about - (void)applicationDidBecomeActive:(UIApplication *)application in your UIApplicationDelegate?
Look at UIApplicationDelegate. -applicationDidBecomeActive: is what you are looking for.
You can also register for notifications in your classes (UIApplicationDidBecomeActiveNotification). This may be simpler to implement than having your app delegate handle everything since you can have, for example, each view controller manage itself.
(Use NSNotificationCenter's -addObserver:selector:name:object: to register, don't forget to unregister during object cleanup, typically in -dealloc.)