Question

I’m trying to create an application that will fetch data from a web API and display it, then continuously refresh the data every 5 seconds or so, but I don’t know the best way to go about doing this.

My first thought was just a simple timer, doing something like what was done in this question, but I’m worried that I may mess it up and have the timer continue running in the background when it shouldn’t be (like if the user leaves the page). Am I worried over something that isn’t going to actually happen? Is this a good way to go about doing what I’m trying to do, or is there a more efficient/safe way of doing this?

Answer 1

When you navigate outside app, timer will not continue, but when you navigate to another page inside app, timer will continue. You can prevent it this way:

    System.Windows.Threading.DispatcherTimer dt;

    public MainPage()
    {
        InitializeComponent();
        dt = new System.Windows.Threading.DispatcherTimer();
        dt.Interval = new TimeSpan(0, 0, 0, 0, 1000); // 1000 Milliseconds
        dt.Tick += new EventHandler(dt_Tick);
    }

    protected override void OnNavigatedFrom(System.Windows.Navigation.NavigationEventArgs e)
    {
        dt.Stop();
    }

    protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
    {
        dt.Start();
    }

    void dt_Tick(object sender, EventArgs e)
    {
        listBox1.Items.Add(listBox1.Items.Count + 1); // for testing
    }

    private void PageTitle_Tap(object sender, GestureEventArgs e)
    {
        NavigationService.Navigate(new Uri("/Page1.xaml", UriKind.Relative)); // for testing
    }

Moreover, if you are just checking for data which most time is not changed, consider using push notifications.