Getting Started with Windows Phone Alarms

by WindowsPhoneGeek

In this article I am going to talk about how to use Alarms in  Windows Phone applications.

Basically an Alarm is one of the two types of scheduled actions that are available in windows Phone Mango It allows you to specify a sound file to play when the notification is launched. A scheduled notification is a dialog box that pops up on the screen at a specified time, similar to the notifications displayed by the phone's built-in applications.The dialog box displays some customizable text information to the user and allows the user to dismiss the notification or postpone it until later. If the user taps the notification, the application that created it is launched.

For reference take a look at the MSDN documentation.

NOTE: Note that the schedules for these notifications are accurate only within a range of one minute. In other words, the notification can be launched up to one minute after it was scheduled.

Getting Started

Step1: Create a Windows Phone 7 application project.

Step2: Add a new page and name it "NewAlarmPage" and add the following code inside NewAlarmPage.xaml:

<StackPanel Grid.Row="1" Orientation="Vertical">
    <!--<TextBlock Text="Title:" />
    <TextBox x:Name="txtTitle" Text="alarm title" />-->
    
    <TextBlock Text="Content:" />
    <TextBox x:Name="txtContent" Text="alarm content" />
    
    <TextBlock Text="Seconds to start:" />
    <TextBox x:Name="txtSeconds" Text="10" />
    
    <StackPanel Orientation="Horizontal">
        <Button x:Name="btnDone" Content="done" Click="btnDone_Click" />
        <Button x:Name="btnCancel" Content="cancel" Click="btnCancel_Click" />
    </StackPanel>
</StackPanel>

Step3: Add the following code inside NewAlarmPage.cs.

NOTE: In the below example we use Guid.NewGuid().ToString();  since alarm names must be unique .

NOTE: The value of BeginTime must be after the current time. Set the BeginTime time property in order to specify when the alarm should be shown.

NOTE: ExpirationTime must be after BeginTime .The value of the ExpirationTime property specifies when the schedule of the alarm expires. This is very useful for recurring alarms, ex: show alarm every day at 5PM but stop after 10 days from now.

NOTE: Do not forget to call this.NavigationService.GoBack(); so that the app will navigate to the main page.

private void btnDone_Click(object sender, RoutedEventArgs e)
{
    string alarmName = Guid.NewGuid().ToString();
    // use guid for alarm name, since alarm names must be unique
    Alarm alarm = new Alarm(alarmName);
    // NOTE: setting the Title property is not supported for alarms
    //alarm.Title = this.txtTitle.Text;
    alarm.Content = this.txtContent.Text;
    double seconds = 10.0;
    double.TryParse(this.txtSeconds.Text, out seconds);

    //NOTE: the value of BeginTime must be after the current time
    //set the BeginTime time property in order to specify when the alarm should be shown
    alarm.BeginTime = DateTime.Now.AddSeconds(seconds);

    // NOTE: ExpirationTime must be after BeginTime
    // the value of the ExpirationTime property specifies when the schedule of the alarm expires
    // very useful for recurring alarms, ex:
    // show alarm every day at 5PM but stop after 10 days from now
    alarm.ExpirationTime = alarm.BeginTime.AddSeconds(5.0);

    alarm.RecurrenceType = RecurrenceInterval.None;
    ScheduledActionService.Add(alarm);

    this.NavigationService.GoBack();
}

Step4: Add the following code in order to handle the Click event of the Cancel button:

private void btnCancel_Click(object sender, RoutedEventArgs e)
{
    this.NavigationService.GoBack();
}

Step5: Add the following code inside MainPage.xaml to display a list of alarms:

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="*" />
        <RowDefinition Height="Auto" />
    </Grid.RowDefinitions>

    <ListBox x:Name="lbAlarms" Grid.Row="0">
        <ListBox.ItemTemplate>
            <DataTemplate>
                <StackPanel Margin="0,0,0,17" Width="432" Height="78">
                    <TextBlock Text="{Binding Content}" TextWrapping="Wrap" Style="{StaticResource PhoneTextExtraLargeStyle}"/>
                    <TextBlock Text="{Binding BeginTime}" TextWrapping="Wrap" Margin="12,-6,12,0" Style="{StaticResource PhoneTextSubtleStyle}"/>
                </StackPanel>
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox>
    
    <StackPanel Grid.Row="1" Orientation="Horizontal">
        <Button x:Name="btnAddNewAlarm" Content="Add New" Click="btnAddNewAlarm_Click" />
        <Button x:Name="btnRemoveSelectedAlarm" Content="Remove Selected" Click="btnRemoveSelectedAlarm_Click" />
    </StackPanel>
</Grid>

Step6: In MainPage.cs, implement a RefreshAlarmList method that we will call to refresh the list of alarms

private void RefreshAlarmList()
{
    IEnumerable<Alarm> alarms = ScheduledActionService.GetActions<Alarm>();
    this.lbAlarms.ItemsSource = alarms;
}

Step7: Handle the Click event of the "Add New" button to implement navigation to the NewAlarmPage.xaml page

private void btnAddNewAlarm_Click(object sender, RoutedEventArgs e)
{
    this.NavigationService.Navigate(new Uri("/NewAlarmPage.xaml", UriKind.Relative));
}

Step8: Handle the Click event of the "Remove Selected" button to implement removing of alarms

private void btnRemoveSelectedAlarm_Click(object sender, RoutedEventArgs e)
{
    Alarm selectedAlarm = this.lbAlarms.SelectedItem as Alarm;
    if (selectedAlarm != null)
    {
        ScheduledActionService.Remove(selectedAlarm.Name);
        this.RefreshAlarmList();
    }
}

Step9: Finally in MainPage.cs, override the OnNavigatedTo method and call RefreshAlarmList to refresh the list of alarms when the user navigates to MainPage.xaml

protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
{
    base.OnNavigatedTo(e);

    this.RefreshAlarmList();
}

That was all about getting started with Windows Phone alarms.  You can find the full source code here:

I hope that the article was helpful.

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Comments

<ListBox x:Name="lbAlarms" Grid.Row="0" Height="297" VerticalAlignment="Top" Margin="20,192,-20,0" ItemContainerStyle="{StaticResource ListBoxItemStyle1}" SelectionMode="Multiple">