Xamarin.Forms custom renderer for an Entry that forcibly shows/hides the keyboard on demand. Useful when Entry.Focus() and Entry.Unfocus() does not work as intended.

KeyboardEntry.cs

using Xamarin.Forms;

namespace Project.Controls
{
    public class KeyboardEntry : Entry
    {
        #region ShowKeyboardProperty

        public static readonly BindableProperty ShowKeyboardProperty = BindableProperty.Create<KeyboardEntry, bool>(p => p.ShowKeyboard, default(bool));

        public bool ShowKeyboard
        {
            get
            {
                return (bool)GetValue(ShowKeyboardProperty);
            }
            set
            {
                SetValue(ShowKeyboardProperty, value);
            }
        }

        #endregion
    }
}

KeyboardEntryRenderer_Android.cs

using Xamarin.Forms.Platform.Android;
using Project.Controls;
using Project.Droid.Renderers;
using Xamarin.Forms;
using Android.Views.InputMethods;
using System.ComponentModel;

[assembly: ExportRenderer(typeof(KeyboardEntry), typeof(KeyboardEntryRenderer))]
namespace Project.Droid.Renderers
{
    class KeyboardEntryRenderer : EntryRenderer
    {
        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);
            if (e.PropertyName == KeyboardEntry.ShowKeyboardProperty.PropertyName)
            {
                ToggleKeyboard();
            }
        }

        /// <summary>
        /// Shows or hides the keyboard
        /// </summary>
        private void ToggleKeyboard()
        {
            if (Control != null)
            {
                InputMethodManager inputMethodManager = (InputMethodManager)Control.Context.GetSystemService(Android.Content.Context.InputMethodService);
                if (((KeyboardEntry)Element).ShowKeyboard)
                {
                    inputMethodManager.ShowSoftInput(Control, ShowFlags.Forced);
                    inputMethodManager.ToggleSoftInput(ShowFlags.Forced, HideSoftInputFlags.ImplicitOnly);
                }
                else
                {
                    inputMethodManager.HideSoftInputFromWindow(Control.WindowToken, 0);
                }
            }
        }
    }
}

KeyboardEntryRenderer_IOS.cs

using Project.Controls;
using Project.iOS.Renderers;
using Foundation;
using System;
using System.ComponentModel;
using UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;

[assembly: ExportRenderer(typeof(KeyboardEntry), typeof(KeyboardEntryRenderer))]
namespace Project.iOS.Renderers
{
    class KeyboardEntryRenderer : EntryRenderer
    {
        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);
            if (e.PropertyName == KeyboardEntry.ShowKeyboardProperty.PropertyName)
            {
                ToggleKeyboard();
            }
        }

        /// <summary>
        /// Shows or hides the keyboard
        /// </summary>
        private void ToggleKeyboard()
        {
            if (Control != null)
            {
                if (((KeyboardEntry)Element).ShowKeyboard)
                {
                    if (Focused)
                    {
                        BecomeFirstResponder();
                    }
                }
                else
                {
                    this.Control.ShouldReturn += (textField) => {
                        textField.ResignFirstResponder();
                        return true;
                    };
                }
            }
        }
    }
}

Usage

// Hide keyboard from an Entry
entry.ShowKeyboard = false;

// Show keyboard from an Entry
entry.ShowKeyboard = true;