Setting the Focus to an Entry in Xamarin.Forms

Question

This is just a simplified example, but I'm trying to set this up so that when I open up this page in my Application, the first thing that happens is the keyboard pops up ready for the user to type in their response to an Entry field.

    var namelabel = new Label { Text = "What is your name?" };
    var nameentry = new Entry { Placeholder = "Type here..." };
    var colorlabel = new Label { Text = "What's your fav color?" };
    var colorentry = new Entry { Placeholder = "Type here..." };
    Content = new StackLayout {
       Spacing = 15,
       Children = { namelabel, nameentry, colorlabel, colorentry }
    };

How can I set the focus of the page to the first entry? And additionally, after the user has put in their first entry, how could I set this up so that the user could press a "Next" Button on the Keyboard (or something along those lines) and the app will take them to fill in the second entry?

Answer 1

Use the Focus method

nameentry.Focus();

If you want the focus to be set when your page appears, you should probably do this in the OnAppearing method

    protected override void OnAppearing ()
    {
        base.OnAppearing ();

        nameentry.Focus();
    }

Answer 2

In one of my projects I did something like this. Please try the following example:

public class EntryFocusBehavior : Behavior<Entry>
{
    public string NextFocusElementName { get; set; }

    protected override void OnAttachedTo(Entry bindable)
    {
        base.OnAttachedTo(bindable);
        bindable.Completed += Bindable_Completed;
    }

    protected override void OnDetachingFrom(Entry bindable)
    {
        bindable.Completed -= Bindable_Completed;
        base.OnDetachingFrom(bindable);
    }

    private void Bindable_Completed(object sender, EventArgs e)
    {
        if (string.IsNullOrEmpty(NextFocusElementName))
            return;

        var parent = ((Entry)sender).Parent;
        while (parent != null)
        {
            var nextFocusElement = parent.FindByName<Entry>(NextFocusElementName);
            if (nextFocusElement != null)
            {
                nextFocusElement.Focus();
                break;
            }
            else
            {
                parent = parent.Parent;
            }
        }
    }
}

And then XAML:

!!! Please let me know if I made a mistake in the code.

Answer 3

Just inside OnAppearing(), add the following code,

protected async override void OnAppearing()
{
    await Task.Run(async () =>
    {
        await Task.Delay(100);
        Device.BeginInvokeOnMainThread(async () =>
        {
            txtName.Focus();
        });
    });
}

Note: txtName is the reference name of your Entry Field.

Answer 4

Focus() needs to have a visible page and visible control to focus on.

The issue in my case was that is is necessary that OnAppearing has to exit before a page is shown / visible. What helped in my case is to wait for page visibility in a different thread and then set the focus in the main (UI) thread:

protected override void OnAppearing()
        {
            base.OnAppearing();

            Task.Run(() =>
            {
                while (!IsVisible)
                {
                    Debug.WriteLine("Page not visible, waiting...");
                    Task.Delay(50).Wait();
                }

                Device.BeginInvokeOnMainThread(() =>
                {
                    bool gotFocus = Entry.Focus();
                    if (!gotFocus)
                        Debug.WriteLine("Could not set focus.");
                });
            });
        }