MartinZikmund

<StackPanel Orientation="Horizontal">
    <BitmapIcon UriSource="ms-appx:///Assets/windows.png" />
    <BitmapIcon UriSource="ms-appx:///Assets/windows.png" ShowAsMonochrome="False" />
</StackPanel>

MartinZikmund

private void Calendar_CalendarViewDayItemChanging(CalendarView sender, CalendarViewDayItemChangingEventArgs args)
{
    if (_highlightedDates.Contains(args.Item.Date))
    {
        HighlightDay(args.Item);
    }
    else
    {
        UnHighlightDay(args.Item);
    }

MartinZikmund

private static void HighlightDay(CalendarViewDayItem displayedDay)
{
    displayedDay.Background = new SolidColorBrush(Colors.Red);
}

private static void UnHighlightDay(CalendarViewDayItem displayedDay)
{
    displayedDay.Background = new SolidColorBrush(Colors.Transparent);
}

MartinZikmund

private void UpdateCalendar()
{
    var displayedDays = Calendar.FindDescendants<CalendarViewDayItem>();
    foreach (var displayedDay in displayedDays)
    {
        if (_highlightedDates.Contains(displayedDay.Date.Date))
        {
            HighlightDay(displayedDay);
        }
        else

MartinZikmund

using Microsoft.Toolkit.Uwp.UI.Extensions;

MartinZikmund

private void Add_Click(object sender, RoutedEventArgs e)
{
    _highlightedDates.Add(Picker.Date.Date);
    UpdateCalendar();
}

MartinZikmund

private void Add_Click(object sender, RoutedEventArgs e)
{
    _highlightedDates.Add(Picker.Date.Date);
    UpdateCalendar();
}

MartinZikmund

private List<DateTimeOffset> _highlightedDates = new List<DateTimeOffset>();

MartinZikmund

<StackPanel Padding="20" Spacing="20">
    <DatePicker x:Name="Picker" />
    <Button Click="Add_Click">Add</Button>
    <CalendarView CalendarViewDayItemChanging="Calendar_CalendarViewDayItemChanging" x:Name="Calendar" />
</StackPanel>

MartinZikmund

<ItemGroup>
   <ImageAsset Include="Media.xcassets\AppIcon.appiconset\ipad-76x76%402x.png" />   
   ...
</ItemGroup>