ListView SelectedItem can't set in code

Hello,

You need to use data binding to make ListView aware of the SelectedItem change and trigger the ItemSelected event by emitting a broadcast via the OnPropertyChanged method.

Please refer to the following steps:

Step 1. Implement the INotifyPropertyChanged interface in ViewModel:

MainViewModel : INotifyPropertyChanged
{
	public event PropertyChangedEventHandler PropertyChanged; 
	public void OnPropertyChanged([CallerMemberName] string name = "") =>
	PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
}

Step 2. Implement the property for binding to SelectedItem:

private Item selItem; 

public Item SelItem 
{
    get
    {
        return selItem;
    }
    set
    {
        if (value != selItem)
        {
            selItem = value;
            OnPropertyChanged(); // reports this property has changed.
        }
    }
}

Step 3. Set SelItem in ViewModel, such as SelItem = Items[1]; // Items is binding to ItemsSource of ListView.

Step 4. Binding the ViewModel to ListView:

// in the page code behind
BindingContext = new MainViewModel();

// in xaml
<ListView ItemSelected="vegColl_ItemSelected" ItemsSource="{Binding Items}" SelectedItem="{Binding SelItem,Mode=TwoWay}">

Best Regards,

Alec Liu.

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