In my app I use Shell tabs. One of the tab is ContentPage containing ListView.
When I click on any of the elements of ListView I am navigating to another View, and after navigation back ListView elements are disabled (see images in the bottom links).
How can I fix it?
Checked facts:
- The bug only occurs on iOS, the application works correctly on Android
- ListView's Selected element is null
- The bug is not related to passing a reference to an element of ListView's ObservableCollection
I have escaping bug scenario, but it is not a problem salvation:
When app initialized click to another tab and return to problem tab back.
Source:
View with Shell (RayMainPage.xaml):
<?xml version="1.0" encoding="utf-8"?>
<Shell xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:views="clr-namespace:RayHelper"
x:Class="RayHelper.RayMainPage">
<TabBar>
<Tab Title="Приюты"
Icon="search">
<ShellContent ContentTemplate="{DataTemplate views:HospiceListPage}" />
</Tab>
<Tab Title="Фонд Рэй"
Icon="help">
<ShellContent ContentTemplate="{DataTemplate views:RayProfilePage}" />
</Tab>
<Tab Title="Рейтинг"
Icon="rank">
<ShellContent ContentTemplate="{DataTemplate views:UsersRankPage}" />
</Tab>
<Tab Title="Пользователь"
Icon="profile">
<ShellContent ContentTemplate="{DataTemplate views:UserProfilePage}" />
</Tab>
</TabBar>
</Shell>
View with ListView (HospiceListPage.xaml):
<?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="RayHelper.HospiceListPage"
Title="Список приютов">
<ContentPage.Resources>
...
</ContentPage.Resources>
<StackLayout>
<ListView x:Name="HospiceList"
ItemsSource="{Binding Hospices}"
SelectionMode="None">
<ListView.ItemTemplate>
<DataTemplate>
<TextCell
Text="{Binding Name}"
Detail="{Binding Address}"
Command="{Binding Source={x:Reference Name=HospiceList}, Path=BindingContext.OpenHospiceProfileCommand}"
CommandParameter="{Binding Source={RelativeSource Self}, Path=BindingContext}"/>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</ContentPage>
and ViewModel for View with ListView (HospiceListPageViewModel.cs)
usings ...
namespace RayHelper.ViewModels
{
public class HospiceListPageViewModel : MainViewModel
{
private ObservableCollection<Hospice> _hospices;
public ObservableCollection<Hospice> Hospices
{
get => _hospices;
set => SetProperty(ref _hospices, value);
}
public IMvxAsyncCommand<Hospice> OpenHospiceProfileCommand { get; }
public HospiceListPageViewModel()
{
OpenHospiceProfileCommand = new MvxAsyncCommand<Hospice>(OpenHospiceProfileAsync);
Hospices = new ObservableCollection<Hospice>();
LoadData();
}
private async void LoadData()
{
var hospices = await GetHospices();
foreach (var hospice in hospices)
{
Hospices.Add(hospice);
}
}
protected override string ClassName => nameof(HospiceListPageViewModel);
private async Task<IEnumerable<Hospice>> GetHospices()
{
try
{
var hospices = await RayHelperClient.GetHospices().ConfigureAwait(false);
hospices.Sort();
return hospices;
}
catch (Exception e)
{
...
}
return Enumerable.Empty<Hospice>();
}
private async Task OpenHospiceProfileAsync(Hospice hospice)
{
await Navigation.PushAsync(new HospiceProfilePage(hospice));
}
}
}
Images: