I have an app which supports background monitoring. For my app to be able to register background movement of device I must call startMonitoringSignificantLocationChanges(). However, at some point in my code I must also call startUpdatingLocation().
My question is, if I call startMonitoringSignificantLocationChanges() and later in my code I call startUpdatingLocation(), will significant monitoring be overridden? Specifically, if I terminate my app will my location manager still receive updates on significant location changes?
After a few testings I’ve come to a conclusion that even if “live” location updates are activated, significant location changes notifications will still be received while running app in background or when terminated. Hope others will find this useful.
Related
Is it possible to update location when application is in suspended/terminate state.
i want to update location every 500 meters when app is in suspended/terminate state.
thanks in advance.
When terminated the only real way to get updates is to use Region Monitoring but you will only get major updates so I doubt it will work for 500 meters.
From the documentation:
If your app is terminated either by a user or by the system, the
system doesn't automatically restart your app when new location
updates arrive. A user must explicitly relaunch your app before the
delivery of location updates resumes. The only way to have your app
relaunched automatically is to use region monitoring or
significant-change location service. However, when a user disables the
Background App Refresh setting either globally or specifically for
your app, the system doesn't relaunch your app for any location
events, including significant change or region monitoring events.
Further, while Background App Refresh is off your app won't receive
significant change or region monitoring events even when it's in the
foreground.
There are good reasons for this. Firstly people don't want apps that 'snoop' on them all the time and even if there is a good reason imagine having 10 apps doing this constantly. It's going to start causing you performance and battery life issues.
EDIT
There appears to be some confusion by a lot of people over this issue so I will attempt to clear things up a bit.
Your app is NOT supposed to be continually tracking location while terminated (or suspended really). You are just not allowed to do this both for privacy reasons and so that you don't drain the battery excessively.
While your app is in the foreground you can use location services via startUpdatingLocation to monitor the device location. Assuming the app has been granted permission this will use all available hardware (GPS, WiFi, Cellular).
Now from the documentation itself:
If you start this service and your app is suspended, the system stops
the delivery of events until your app starts running again (either in
the foreground or background). If your app is terminated, the delivery
of new location events stops altogether. Therefore, if your app needs
to receive location events while in the background, it must include
the UIBackgroundModes key (with the location value) in its Info.plist
file.
So once suspended and terminated your options are really to monitor regions and to monitor for significant location changes. Neither of these are particularly accurate or frequent. One reason for this is that they only use low power methods to get the position (WiFi and Cellular) they don't use the GPS.
So no accurate and/or frequent location tracking while an app is suspended or terminated. This just has to be accepted and you need to design your apps accordingly.
let locationManager = CLLocationManager()
locationManager.startMonitoringSignificantLocationChanges()
After returning a current location fix, the receiver generates update events only when a significant change in the user’s location is detected. It does not rely on the value in the distanceFilter property to generate events
If you start this service and your app is subsequently terminated, the system automatically relaunches the app into the background if a new event arrives. In such a case, the options dictionary passed to the application(:willFinishLaunchingWithOptions:) and application(:didFinishLaunchingWithOptions:) methods of your app delegate contains the key location to indicate that your app was launched because of a location event. Upon relaunch, you must still configure a location manager object and call this method to continue receiving location events. When you restart location services, the current event is delivered to your delegate immediately. In addition, the location property of your location manager object is populated with the most recent location object even before you start location services.
Apps can expect a notification as soon as the device moves 500 meters or more from its previous notification. It should not expect notifications more frequently than once every five minutes. If the device is able to retrieve data from the network, the location manager is much more likely to deliver notifications in a timely manner.
Hope It helps
I require the user running location and route map path, When an application is Terminate or Background mode.
Currently I am using significant location for application kill mode, but we are not getting proper distance and route.
Because didUpdateLocations is called after some specific interval so that I am not getting proper distance.
Please guide.
According to Apple docs :
Apps can expect a notification as soon as the device moves 500 meters
or more from its previous notification. It should not expect
notifications more frequently than once every five minutes. If the
device is able to retrieve data from the network, the location manager
is much more likely to deliver notifications in a timely manner.
This is why startMonitoringSignificantLocationChanges() would not work reliably for tracking user location change other than driving/public-transport.
Now, coming back to your problem of having to track user location when app is terminated, unfortunately you cannot track location when the app is terminated
If your app is terminated either by a user or by the system, the system doesn’t automatically restart your app when new location updates arrive. A user must explicitly relaunch your app before the delivery of location updates resumes. The only way to have your app relaunched automatically is to use region monitoring or the significant-change location service.
I'm doing an app to trigger a local notification when a region is entered.
However, sometimes when the phone is locked, the notifications didn't pop up even I've been in the region area for a while. The notification popup will show only when the power/home button is pressed(phone still in locked mode).
In general, all seems to be working except that sometimes the notification will show only when power/home button is pressed to awake the phone although it is still locked.
Hope someone can enlighten me please! =)
According to the developer documentation. In core-location framework, two services can give you the current location information.
The standard location service is a configurable, general-purpose solution for getting location data and tracking location changes for the specified level of accuracy.
The significant-change location service delivers updates only when there has been a significant change in the device’s location, such as 500 meters or more.
You need to use standard location services to keep monitoring location in background
If your iOS app must keep monitoring location even while it’s in the background, use the standard location service and specify the location value of the UIBackgroundModes key to continue running in the background and receiving location updates. (In this situation, you should also make sure the location manager’s pausesLocationUpdatesAutomatically property is set to YES to help conserve power.)
I'm wondering if, in iOS8 with all possible background-modes turned on, the app will be woken up after termination to deliver location updates using the standard-location updates monitoring?
I've read all possible documentations, but I find it quite confusing because it at one point says the device will wake up the app, and at another point is says the device will not wake up the app when using standard-location updates.
My app needs continuous location updates with a movement-threshold of about 150 meters (max), and therefore the standard-location-monitoring seems appropriate. It also needs to keep getting these updates even if the app is terminated by the system, as it is crucial to the user.
I've come to understand that if using the significant change location monitoring the app will be woken up upon delivery of new data, but I'm still confused about the standard location monitoring when having requested Always authorization and having the background updates for location turned on.
Have anyone tested this, or know what happens? And if the app is not woken up after being terminated by the system, how can I solve that problem?
Thanks.
Standard location is something your app does. Thus your app needs to be running. It can operate in the foreground or you can even run in the background. But if your app is not running, it's not running; there is nothing to track.
Significant location monitoring and region monitoring, on the other hand, are done for you by the system, so it runs even if your app is not running, and you are woken up or launched to receive updates.
I am creating an application that sends updated location to server regardless of app state. I have tried silent push to wake my application in background but it didnt work (it works fine except if my app is killed by user from app switcher). I am using location manager for getting current location.
Does IOS7 provides this feature to launch your application in background (even if app is killed by user from app switcher)??
I have spent five days without any success on this. If anyone can help me that would be highly appreciable.
Thanks in advance!!
If you need precise GPS locations you can set add the "location" value to the UIBackgroundModes array in your Info.plist as described in "UIBackgroundModes location and significant location changes with region monitoring". If you need only approximate locations you can use the startMonitoringSignificantLocationChanges method of CLLocationManager. As it is written in the documentation: "If you start this service and your application is subsequently terminated, the system automatically relaunches the application into the background if a new event arrives."
You can wake your app by using significantlocationchange.
You have to start significant location change while you switch your app to background.
Then system will wake your app after significant location change.
The frequency is not faster than 5 min and for every 500 meters.
You will have to catch the event by checking for LocationKey in didFinishLaunchingWithOptions in projects AppDelegate.