Now that we know how to import the Location Service, let us now learn how to start using it.

To start the Location Service, the Start method of the GeoCoordinateWatcher class needs to be called. Continuing from our previous example, open the MainPage.xaml.cs file and create a variable of type GeoCoordinateWatcher in your MainPage() constructor as:

var locationManager = new GeoCoordinateWatcher();

And declare the locationManager variable in the global scope, by declaring it as a field right after the class initialization.

public partial class MainPage : PhoneApplicationPage
{
GeoCoordinateWatcher locationManager;

Now we call the Start method as:

locationManager.Start();

To quickly get the latitude/longitude data (assuming the application can access location information), add two TextBlock elements to your main XAML file (MainPage.xaml) and name them latitudeText and longitudeText respectively. This is shown in the following screenshot:

Add the following code to MainPage.xaml.cs in the MainPage() constructor, after the locationManager.Start() line:

latitudeText.Text=
locationManager.Position.Location.Latitude.ToString("0.000");
longitudeText.Text =
locationManager.Position.Location.Longitude.ToString("0.000");

Running the example in the emulator will produce the following result:

In the previous example, we assumed that the GPS or other location-determining hardware was ready to return the location information as soon as we requested it. However, this is not true in a real-world scenario, GPS devices may take a few seconds to get a good signal in a remote place. The GeoCoordinateWatcher class implements the StatusChanged event to handle this, returning the status (of type GeoPositionStatus), which could be any of the following based on the device's status:

We define the StatusChanged event handler function immediately after creating the locationManager variable in the MainPage() constructor as:

locationManager.StatusChanged += new
EventHandler<GeoPositionStatusChangedEventArgs>
(locationManager_getStatus);

locationManager_getStatus is our custom-defined function where we handle the statuses for the GeoCoordinateWatcher class, which is defined as:

void locationManager_getStatus(object sender,
GeoPositionStatusChangedEventArgs e)
{
switch (e.Status)
{
case GeoPositionStatus.Initializing:
statusText.Text = "Loading ...";
break;
case GeoPositionStatus.Ready:
latitudeText.Text =
locationManager.Position.Location.Latitude.ToString();
longitudeText.Text =
locationManager.Position.Location.Longitude.ToString();
statusText.Text = "Location Available";
break;
case GeoPositionStatus.Disabled:
statusText.Text = "Disabled";
break;
case GeoPositionStatus.NoData:
statusText.Text = "No Data at this time";
break;
}// end of switch
} // end of locationManager_getStatus

In most cases, you should be able to get the location; however, there could be two reasons for location being disabled:

We cannot help in the first case; however, in the second case we can use the Permission property of the GeoCoordinateWatcher class. Modify the GeoPositionStatus.disabled case from the previous example to the following one:

case GeoPositionStatus.Disabled:
if (locationManager.Permission == GeoPositionPermission.Denied)
{
statusText.Text = "User has disabled location settings";
}
else
statusText.Text = "Disabled";
break;

To display the status of the Location Service, we added one more TextBlock to the UI (via the MainPage.xaml file) and named it statusText, and placed it near the footer of the app as shown in the following screenshot:

There is no way to disable the location settings on the emulator yet, so we tested this example on the phone itself. The following screenshot shows how the application will behave with location settings turned off (see Chapter 1, The Location-based World on how to turn location settings on/off):

You can also specify accuracy for the GeoCoordinateWatcher object by passing an argument of type GeoPositionAccuracy. There are two accuracy levels:

We will modify our GeoCoordinateWatcher object to use the high accuracy level by using the following arguments at the object creation time:

locationManager = new
GeoCoordinateWatcher(GeoPositionAccuracy.High);

It is also a good practice to use the Stop() method wherever possible to turn off the Location Service when not needed, to maximize the battery life of the device.

You can find this example project in the code files for the book under Chapter 2, titled PhoneApp1.

In our previous example we saw how to fetch the location data when the service is ready. We saw a simple way to access the location data from the GeoCoordinateWatcher object; however, there is another event exposed by the GeoCoordinateWatcher class – the PositionChanged event that is fired when the location service detects a change in the position of the Windows Phone device.

Let us now build our Hello Location example that uses both the StatusChanged and PositionChanged events:

You can find this example project in the code files for the book under Chapter 2, titled Hello Location.

Having played with our Hello Location example app, let us now dig more into the Windows Phone location simulator to understand how we can simulate location data in our application.

Open the Hello Location example and run it in Windows Phone Emulator. The Emulator comes with an Additional Tools sidebar, which is activated from the Emulator home screen via the Additional Tools button (>>) as shown in the following screenshot:

Within the Additional Tools sidebar open, select the Location tab, as shown in the following screenshot:

When you run the Hello Location example, the values you get for the latitude/longitude pair by default would be 47.64483 and -122.141197, which is Microsoft's Redmond office. Playing around with the location simulator and the Hello Location application side by side, you will find the location updates happen immediately on the Hello Location app.

You can also search for places using the search input box. A cool feature of the simulator is the ability to save the maps points you have added on the maps. This can be loaded back from the saved file or by manually adding points to simulate your app behavior, by loading the saved locations file (Locations.xml in our case) and hitting the Play all points button as shown in the following screenshot:

The Location.xml file is shown as follows; we added two different cities' latitude/longitude data to it and checked the Hello Location app against it.

<?xml version="1.0" encoding="utf-8"?>
<WindowsPhoneEmulator xmlns=
"http://schemas.microsoft.com/WindowsPhoneEmulator/2009/08/
SensorData">
<SensorData>
<Header version="1" />
<GpsData latitude="48.8596434322625"
longitude="1.49173867702484" />
<GpsData latitude="48.645964012732"
longitude="1.49723184108734" />
<GpsData latitude="19.0227245363093"
longitude="72.8413543701172" />
</SensorData>
</WindowsPhoneEmulator>