ListView Item Selected/Tapped not Working on iOS

Stefan Hodges-Kluck 1 Reputation point
2021-10-27T21:17:50.513+00:00

We have recently implemented ItemSelected on one of our ListView components. It works fine on Android, but on iOS the list items only respond to a user hitting them about 1 out of 10 times. We tried changing our ItemSelected handler to an ItemTapped, but ran into the same issue.

Here are the attributes on our ListView:

x:Name="list"
ItemsSource="{Binding Items}"
SeparatorVisibility="None"
 HasUnevenRows="False"
RowHeight="100"
BackgroundColor="Transparent"
ItemSelected="OnItemSelected"
IsEnabled="{Binding IsBusy, Converter={StaticResource negate}}"

And here is the relevant code behind (though the OnItemSelected event is not fired when tapping, so I think it's failing in the xaml):

    protected override void OnAppearing()
    {
        SetListHeightRequest(list, pageTitle, CTAs);
        base.OnAppearing();
    }

    async void OnItemSelected(object sender, SelectedItemChangedEventArgs args)
    {
        _viewModel.SelectedItem = args.SelectedItem;
        await _viewModel.HandleSelectItemAsync();
    }

    protected void SetListHeightRequest(ListView list, Layout title, Layout ctas)
    {
        list.HeightRequest = Application.Current.MainPage.Height - (title.Height + ctas.Height);
    }
Xamarin
Xamarin
A Microsoft open-source app platform for building Android and iOS apps with .NET and C#.
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2 answers

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  1. Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 26,751 Reputation points Microsoft Vendor
    2021-10-28T08:32:48.477+00:00

    Hello,

    Welcome to our Microsoft Q&A platform!

    I'm so sorry I can't reproduce this issue, I suspect that it caused by the ViewModel, so I display a tableview without ViewModel, it works well.
    XAML

    <ListView  
                 x:Name="list"  
                ItemsSource="{Binding Items}"  
                SeparatorVisibility="None"  
                HasUnevenRows="False"  
                RowHeight="100"  
                BackgroundColor="Transparent"  
                ItemSelected="OnItemSelected">  
                <ListView.ItemTemplate>  
                    <DataTemplate>  
                        <TextCell Text="{Binding }" />  
                    </DataTemplate>  
                </ListView.ItemTemplate>  
            </ListView>   
    

    Code behind

     public ObservableCollection<string> Items { get; set; } = new ObservableCollection<string>();  
            public MainPage()  
            {  
                InitializeComponent();  
                    for (int i = 0; i < 10; i++){  
                    Items.Add(i.ToString());  
                }  
                      
                BindingContext = this;  
                 
            }  
            protected override void OnAppearing()  
            {  
                base.OnAppearing();  
            }  
            async void OnItemSelected(object sender, SelectedItemChangedEventArgs args)  
            {  
                Console.WriteLine("has been selected");  
            }  
    

    Then, I add the ViewMode and Model, it also works.

    XAML

    <DataTemplate>  
        <TextCell Text="{Binding Text}" />  
      </DataTemplate>  
    

    Code behind

    public partial class MainPage : ContentPage  
        {  
            public ItemViewModel Items { get; set; } = new ItemViewModel();  
            public MainPage()  
            {  
                InitializeComponent();  
                BindingContext = Items;  
            }  
            protected override void OnAppearing()  
            {  
                base.OnAppearing();  
            }  
            async void OnItemSelected(object sender, SelectedItemChangedEventArgs args)  
            {  
                Items.SelectedItem = (Item)args.SelectedItem;  
                await Items.TaskHandleSelectItemAsync();  
                  
            }  
        }  
    

    ItemViewModel

     public class ItemViewModel  
        {  
            public ObservableCollection<Item> Items { get; set; } = new ObservableCollection<Item>();  
            public Item SelectedItem { get; set; }  
            public ItemViewModel()  
            {  
                for (int i = 0; i < 10; i++)  
                {  
                   Item item = new Item { Text = i.ToString() };  
                   Items.Add(item);  
                }  
            }  
      
          public async Task  TaskHandleSelectItemAsync()  
            {  
                Console.WriteLine("has been selected" + SelectedItem.Text);  
            }  
        }  
    

    Model

    public class Item  
        {  
            public string Text { get; internal set; }    
        }  
    

    I change the HeightRequest, it also works. The biggest difference is that you use _viewModel and IsEnabled="{Binding IsBusy, Converter={StaticResource negate}}" and SetListHeightRequest , you could try to check these methods.
    In addition, would you mind sharing a demo to me so that I can reproduce this issue and test it?

    Best Regards,
    Wenyan Zhang


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  2. Stefan Hodges-Kluck 1 Reputation point
    2021-11-08T13:43:53.55+00:00

    Yes, it works by adding CachingStrategy="RecycleElement" on the listview's properties