How to handle memory

Question

While exploring with UWP I had a problem with this simple app I was trying. My app shuts down automatically in Windows Phone with 512mb ram beacuse there is too much content and I guess that is making the phone run out of memory.

I wanted to ask which is the right approach to load the content without making the app crash? Should I implement a load more at the end of the screen and load some of the content and hide another on click or is there any other better solution?

I've read a little about UI Virtualization but I don't know how to implement it in this case. An example would be appriciated.

<ScrollViewer HorizontalScrollBarVisibility="Hidden" Height="500"  Loaded="Populate">
     <StackPanel x:Name="ContentsPanel"></StackPanel>
</ScrollViewer>

void Populate(object sender, RoutedEventArgs e)
{
    for (int i = 0; i < 1000; i++)
    {
       ContentsPanel.Children.Add(new TextBlock
       {
           Text = @"ipsumSed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium,
                totam rem aperiam,
                eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo.Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit,
                sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt.Neque porro quisquam est,
                qui dolorem ipsum quia dolor sit amet,
                consectetur,
                adipisci velit,
                sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem.Ut enim ad minima veniam,
                quis nostrum exercitationem ullam corporis suscipit laboriosam,
                nisi ut aliquid ex ea commodi consequatur ? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur,
                vel illum qui dolorem eum fugiat quo voluptas nulla pariatur ? 
                At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."

       });
    }
}

Answer 1

Most of the time when you run out of memory its because you've got large images loaded, or you are are not using/have broken virtualization. This is an overly simplistic rule but, you should not put a stack panel in a scroll viewer. If you find yourself wanting to do that, what you probably want is actually a ListView bound to some sort of ItemsSource (ObservableCollection<T> if you want to be able to add/remove things later, or any IEnumerable<T> if its completely static. If the contents of the list view are homogeneous you can use ListView.ItemTemplate and if the contents are heterogeneous you can use ListView.ItemTemplateSelector to pick a different template for different kinds of items.

When you use a ListView, the XAML runtime will only create enough UI controls for what is currently shown on screen + a little bit on top and bottom to make sure scrolling is smooth. Take note, that this is UI Virtualization, not Content Virtualization, for that you can implement ISupportIncrementalLoading on a class that you bind as an ItemSource.

Edit to Add the requested sample:

<ListView x:Name="contentsList" HorizontalScrollBarVisibility="Hidden" Height="500"  Loaded="Populate">
    <ListView.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding}" /> <!-- this is not actually needed in this example because its actually the default data template for a list view but ive included it for completeness -->
        </DataTemplate>
    </ListView.ItemTemplate>
<ListView>

void Populate(object sender, RoutedEventArgs e)
{
    var madeList = new List<string>()
    for(int i = 0; i < 1000; i++)
    {
        madeList.Add(@"ipsumSed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium,
                totam rem aperiam,
                eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo.Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit,
                sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt.Neque porro quisquam est,
                qui dolorem ipsum quia dolor sit amet,
                consectetur,
                adipisci velit,
                sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem.Ut enim ad minima veniam,
                quis nostrum exercitationem ullam corporis suscipit laboriosam,
                nisi ut aliquid ex ea commodi consequatur ? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur,
                vel illum qui dolorem eum fugiat quo voluptas nulla pariatur ? 
                At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.");

    }
    contentsList.ItemsSource = madeList;
}

Answer 2

You could load more content once you've reached the end of your scrollviewer. How to find that ScrollViewer is scrolled to the end in WPF? provides an example.