Xamarin.Forms set focus from mvvm ViewModel

Question

I'm working on a chat application using Xamarin.Forms.

And I want to avoid to hide the keyboard when the Entry loses focus and button Send is clicked.

How can I do it on Android and iOS?

I use XF, full Mvvm without XAML(only C#)

Updated:

In page class:

private EntrySetBorder _newMessageEntry;
...
_newMessageEntry = new EntrySetBorder
{
    TextColor = Color.Black,
    HorizontalOptions = LayoutOptions.FillAndExpand,
    VerticalOptions = LayoutOptions.End,
    Margin = new Thickness(0, 0, 5, 0)
};

In model class:

var entry = CurrentPage.FindByName<EntrySetBorder>("_newMessageEntry");
entry.Focus();

}

Answer 1

This can be achieved easily by using the FindByName<>() function inside the PCL.
This is one way of doing that:

Entry myEntry = CurrentPage.FindByName<Entry>("YourEntryName");
myEntry.Focus();

You can add that at the end of the click handler of your send button.

Edit:

In your case I think your problem is that your entry is set to private, so I would suggest either expose it as public or expose it using another public property. Two solutions that might work:

public EntrySetBorder _newMessageEntry;
...
_newMessageEntry = new EntrySetBorder
{

    TextColor = Color.Black,
    HorizontalOptions = LayoutOptions.FillAndExpand,
    VerticalOptions = LayoutOptions.End,
    Margin = new Thickness(0, 0, 5, 0)
};

And:

EntrySetBorder entry = CurrentPage.FindByName<EntrySetBorder>("_newMessageEntry");
entry.Focus();

Or you go with this:

private EntrySetBorder _newMessageEntry;
...
_newMessageEntry = new EntrySetBorder
{

    TextColor = Color.Black,
    HorizontalOptions = LayoutOptions.FillAndExpand,
    VerticalOptions = LayoutOptions.End,
    Margin = new Thickness(0, 0, 5, 0)
};
public EntrySetBorder NewMessageEntry => _newMessageEntry;

and :

EntrySetBorder entry = CurrentPage.FindByName<EntrySetBorder>("NewMessageEntry");
entry.Focus();

Please try that :)

Edit 2:

After reviewing your code, and testing it, the final way to fix it was by sending the Entry as a parameter in the command you're using, example:

Inside the page you're creating:

sendButton.CommandParameter = NewMessageEntry; // We're adding the Entry we want to focus as a command parameter.

And inside your PageModel and the command we want to use:

public Command SendCommand
{
    get
    {
        return new Command<Entry>((obj) => //obj here means the parameters we're sending I.E: the entry we set it in the page.
        {
            //The code you want to execute
            Entry entry = obj;
            entry.Focus();
        });
    }
}

Note that I used Entry because I didn't have all the implementation of your custom entry.