12.5. Handling Location Changes in the Background
Problem
You are writing an application whose main functionality is processing location changes, using Core Location. You want the application to retrieve the iOS device location changes even if the application is sent to the background.
Solution
Add the location
value to the
UIBackgroundModes
key of your main
application .plist file, like
so:
<dict> ... ... ... <key>UIBackgroundModes</key> <array> <string>location</string> </array> ... ... ... </dict>
Discussion
When your application is running in the foreground, you can
receive delegate messages from an instance of CLLocationManager
telling you when iOS
detects that the device is at a new location. However, if your
application is sent to the background and is no longer active, the
location delegate messages will not be delivered normally to your
application. They will instead be delivered in a batch when your
application again becomes the foreground application.
If you still want to be able to receive changes in the location
of the user’s device while running in the
background, you must add the location
value to the UIBackground
Modes
key of your
application’s main .plist file,
as shown in this recipe’s Solution. Once in the background, your
application will continue to receive the changes in the device’s
location. Let’s test this in a simple app with just the app
delegate.
What I intend to do in this app is to keep a boolean value in
the app delegate, called
executingInBackground
. When ...
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