Xamarin Forms - ListView - Array - Header

About ListView Group, Jason have provided one article about detailed info. If you still have some problem, you can also take a look the following sample.

Firstly, create class to hold event info.

public class eventmodel
{
    public string eventname { get; set; }
}

Then, a way to group the data, with a heading for each list.

 public class eventlist:List<eventmodel>
{
    public string heading { get; set; }
    public List<eventmodel> events => this;
}

Finally, using Observablecollection to bind to listview. Represents a dynamic data collection that provides notifications when items get added, removed, or when the whole list is refreshed.

public class eventgroup
{
    public ObservableCollection<eventlist> eventgroups { get; set; }
    public eventgroup()
    {
        eventgroups = new ObservableCollection<eventlist>();

        var list1 = new eventlist()
        {
            new eventmodel() { eventname= "Event 1 - Today" },
            new eventmodel() { eventname= "Event 2 - Today" },
            new eventmodel() { eventname= "Event 3 - Today" },
            new eventmodel() { eventname= "Event 4 - Today" }
                                                         
        };
        list1.heading = "Today";
        var list2 = new eventlist()
        {
            new eventmodel() { eventname= "Event 1 - Tomorrow" },
            new eventmodel() { eventname= "Event 2 - Tomorrow" },
            new eventmodel() { eventname= "Event 3 - Tomorrow" },
            new eventmodel() { eventname= "Event 4 - Tomorrow" } 
        };
        list2.heading = "Tomorrow";

        eventgroups.Add(list1);
        eventgroups.Add(list2);

       
    }
}

ListView displaying data.

<ListView IsGroupingEnabled="true" ItemsSource="{Binding eventgroups}">
            <ListView.GroupHeaderTemplate>
                <DataTemplate>
                    <ViewCell>
                        <Label BackgroundColor="Red" Text="{Binding heading}" />
                    </ViewCell>
                </DataTemplate>
            </ListView.GroupHeaderTemplate>

            <ListView.ItemTemplate>
                <DataTemplate>
                    <ViewCell>
                        <Label Text="{Binding eventname}" />
                    </ViewCell>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>

 public partial class Page6 : ContentPage
{
    public Page6()
    {
        InitializeComponent();
        this.BindingContext = new eventgroup();
    }
}

The screenshot: