Life-Cycle Events - Metro Revealed: Building Windows 8 Apps with HTML5 and JavaScript - page 85

//Tiles.sendTileUpdate();
//Tiles.sendBadgeUpdate();
Location.startTracking();
});
}
function performResume(e) {
Location.startTracking();
}
function performSuspend(e) {
var promise = Location.stopTracking();
if (promise) {
var deferral = e.suspendingOperation.getDeferral();
promise.then(function () {
deferral.complete();
});
}
}
})();
Windows provides information about why your application has been sent the activated
event through the kind property of the Event object passed to your handler function. The range
of possible values is enumerated by Windows.ApplicationModel.Activation.ActivationKind .
There are different kinds of activation for different contracts for printing, for opening a file, for
working with a device camera, and, of course, for handling search requests. By checking the
value of the kind property, I can discover whether the activated event has been sent for a
search request:
…
if (e.kind == actNS.ActivationKind.search) {
Search.searchAndSelect(e.queryText);
}
…
The search term that the user has provided is available through the event's queryText prop-
erty. If my activated event has been sent for a search request, then I call the searchAndSelect
function, passing in the queryText value. This has the effect of locating and selecting the first
matching item in the grocery list.
Ensuring Application Setup
My technique for servicing search requests relies on the performInitialSetup function having
been called before I call searchAndSelect , because I rely on the view model and its associated
bindings to translate a change in the selectedItemIndex property into changes in the display.
The problem is that the search-related activated event can have two meanings. If my app
is already running, the search activated event means just “perform this search.” But, if my app
isn't running, then the event means “start the app and perform this search.” Working out which
meaning I am dealing with is important. You get only one activated event, even if your app
isn't running when the user initiated the search.