Xamarin Forms: Menggunakan Context Action pada ListView

Pada artikel kali ini saya akan menjelaskan bagaimana menggunakan Context Action yang ada di dalam kontrol ListView.

Context Action adalah tombol berupa bar yang akan muncul ketika pengguna melakukan left-swiped pada iOS dan long-pressed pada Android.

1. Tambahkan halaman xaml baru dengan nama ListViewContextAction.xaml, kemudian tambahkan kode berikut:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="Bab3.ListViewContextAction">
  <ContentPage.Padding>
    <OnPlatform x:TypeArguments="Thickness">
      <OnPlatform.iOS>10,20,10,5</OnPlatform.iOS>
      <OnPlatform.Android>10,5,10,5</OnPlatform.Android>
    </OnPlatform>
  </ContentPage.Padding>
  
  <ListView ItemsSource="{Binding ListItems}" RowHeight="100" BackgroundColor="Black" HasUnevenRows="True">
    <ListView.ItemTemplate>
      <DataTemplate>
        <ViewCell>
          <ViewCell.ContextActions>
            <MenuItem Text="More" Command="{Binding MoreCommand}" />
            <MenuItem Text="Delete" Command="{Binding DeleteCommand}" IsDestructive="True" />
          </ViewCell.ContextActions>
          <StackLayout HorizontalOptions="StartAndExpand" Orientation="Horizontal" Padding="5,10,5,15">
            <StackLayout HorizontalOptions="StartAndExpand" Orientation="Vertical">
              <Label HorizontalOptions="Start" FontSize="20" FontAttributes="Bold" TextColor="White" Text="{Binding Title}"/>
              <Label HorizontalOptions="Start" FontSize="12" FontAttributes="Bold" TextColor="White" Text="{Binding Description}"/>
            </StackLayout>
            <Label HorizontalOptions="End" FontSize="25" TextColor="Aqua" Text="{Binding Price}"/>
          </StackLayout>
        </ViewCell>
      </DataTemplate>
    </ListView.ItemTemplate>
  </ListView>
</ContentPage>

2. Buat class ListItem yang diturunkan dari BindableObject

        public class ListItem : BindableObject
        {
            public string Source { get; set; }
            public string Title { get; set; }
            public string Description { get; set; }
            public string Price { get; set; }

            private Command moreCommand;

            public Command MoreCommand
            {
                get { return moreCommand; }
                set { moreCommand = value; OnPropertyChanged("MoreCommand"); }
            }

            private Command deleteCommand;
            public Command DeleteCommand
            {
                get { return deleteCommand; }
                set { deleteCommand = value; OnPropertyChanged("DeleteCommand"); }
            }

            public ListItem()
            {
                MoreCommand = new Command(MoreRequested);
                deleteCommand = new Command(DeleteRequested);
            }

            void MoreRequested()
            {
                MessagingCenter.Send<ListItem>(this, "MoreRequested");
            }

            void DeleteRequested()
            {
                MessagingCenter.Send<ListItem>(this, "DeleteRequested");
            }
        }

3. Buat class ViewModel untuk membinding data pada kontrol ListView.

    public class ListViewContextActionViewModel : BindableObject
    {
        readonly Func<string, string, string, Task> displayAlertAction;

        private List<ListItem> listItems;

        public List<ListItem> ListItems
        {
            get { return listItems; }
            set { listItems = value; OnPropertyChanged("ListItems"); }
        }

        public ListViewContextActionViewModel(Func<string, string, string, Task> displayAlertAction)
        {
            this.displayAlertAction = displayAlertAction;
            ListItems = new List<ListItem> {
                new ListItem {Title = "First", Description="1st item", Price="$100.00"},
                new ListItem {Title = "Second", Description="2nd item", Price="$200.00"},
                new ListItem {Title = "Third", Description="3rd item", Price="$300.00"}
            };

            MessagingCenter.Subscribe<ListItem>(this, "MoreRequested", MoreRequested);
            MessagingCenter.Subscribe<ListItem>(this, "DeleteRequested", DeleteRequested);
        }

        void MoreRequested(ListItem listItem)
        {
            displayAlertAction.Invoke("More", listItem.Title + " more was clicked", "OK");
        }

        void DeleteRequested(ListItem listItem)
        {
            displayAlertAction.Invoke("Delete", listItem.Title + " delete was clicked", "OK");
   
        }
}

3. Terakhir tambahkan kode berikut pada file ListViewContextAction.xaml.cs

    public partial class ListViewContextAction : ContentPage
    {
        public ListViewContextAction()
        {
            InitializeComponent();

            BindingContext = new ListViewContextActionViewModel(DisplayAlert);
        }
    }

4. Jalankan program, maka anda dapat melihat hasilnya sebagai berikut:

image

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About Erick Kurniawan

IT Trainer, Consultant, & Microsoft Azure MVP Actual Training (http://actual-training.com)
This entry was posted in Cross Platform Mobile Development, Xamarin Forms and tagged , , , , , . Bookmark the permalink.

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