iOS 7 Programming Cookbook

16.5. 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

Select your project file in the Navigator of Xcode. Then, from the Capabilities section, switch on the Background Modes subsection. After the list of background modes is given to you, tick on the Location switch.

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 However, if your application is sent to the background and is no longer active, the location delegate messages will not be delivered normally to your application.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 enable the Location updates capability of your app, as described in the Solution section of this recipe. 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 the app goes to the ...