How to dismiss keyboard with cancellation token after certain duration

Mobile: How to dismiss keyboard with cancellation token after certain duration

The concept is very simple:
I started with static variable: CancellationTokenSource.
Instantiate the variable outside the 'TextChanged' event.
Within the 'text changed' event,  cancel the token every time when user enter a text.
Reinitialise the cancellationTokenSource, because you need it for the delay task, a task to dismiss the keyboard.


Before that, I have a custom search view, which is a view that consists of an entry field with a magnifying glass, plus a binding to activity indicator (loading spinner).

Instead of using the normal element 'entry',  I have a custom element here:
public class SearchEntry : Entry {}

And, here is my custom search view:
public class SearchView : StackLayout
    {
        public event EventHandler<TextChangedEventArgs> TextChanged;

        public static readonly BindableProperty IndicatorRunningProperty =
            BindableProperty.Create("IndicatorRunning", typeof(bool), typeof(SearchView), false);

        public bool IndicatorRunning
        {
            get { return (bool)GetValue(IndicatorRunningProperty); }
            set { SetValue(IndicatorRunningProperty, value); }
        }

        private ActivityIndicator indicator;
        public Entry entry;

        public new event EventHandler<FocusEventArgs> Focused;
        public new event EventHandler<FocusEventArgs> Unfocused;

        public SearchView() {
            entry = new SearchEntry () {
                HorizontalOptions = LayoutOptions.FillAndExpand,
                VerticalOptions = LayoutOptions.Center,
                BackgroundColor = Color.White,
                Placeholder = string.Format ("Search for someone"),
            };
            entry.TextChanged += (object sender, TextChangedEventArgs e) => {
                if (TextChanged != null) {
                    TextChanged (this, e);
                }
            };
            entry.Focused += (object sender, FocusEventArgs e) => {
                if(Focused != null) {
                    Focused(this, e);
                }
            };
            entry.Unfocused += (object sender, FocusEventArgs e) => {
                if(Unfocused != null) {
                    Unfocused(this, e);
                }
            };
            indicator = new ActivityIndicator () {
                WidthRequest = 27,
                HeightRequest = 27,
                VerticalOptions = LayoutOptions.CenterAndExpand,
            };
            indicator.SetBinding (ActivityIndicator.IsRunningProperty, new Binding("IndicatorRunning", BindingMode.TwoWay,source:this));

            var image = new Image () {
                Source = "ic_search.png",
                HeightRequest = 24,
                WidthRequest = 24
            };
            var searchEntryStack = new RoundedStackLayout () {
                BackgroundColor = Color.White,
                CornerRadius = 5f,
                HeightRequest = 27,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Orientation = StackOrientation.Horizontal,
                Padding = new Thickness (10, 0, 10, 0),
                Spacing = Device.OnPlatform (10, 0, 0),
                Children = { image, entry, indicator }
            };
            HorizontalOptions = LayoutOptions.FillAndExpand;
            BackgroundColor = StyleHelpers.NavigationPageBgColor;
            Padding = new Thickness (20, 10, 20, 10);
            Spacing = 0;
            HeightRequest = 47;
            Orientation = StackOrientation.Horizontal;
            Children.Add (searchEntryStack);
        }

        new public void Unfocus() {
            entry.Unfocus ();
        }

        public void Clear() {
            entry.Text = string.Empty;
        }
    } 



Cool, over here is the core of how to use the token cancellation source to dismiss keyboard after certain interval or duration:

Declare a static variable first:
public static CancellationTokenSource tokenSource;


tokenSource = new CancellationTokenSource();
            searchView.TextChanged += (sender, e) => {    
                //Do something here....                 //Everytime when user press, then cancel the token. Then Re-init the token. 
                //Create a task that will complete after time delay with the cancellation token.
                tokenSource.Cancel();
                tokenSource = new CancellationTokenSource();
                var unfocusTask = Task.Delay(3000, tokenSource.Token);
                unfocusTask.ContinueWith(t=>{
                    if (!t.IsCanceled){
                        Device.BeginInvokeOnMainThread(()=>{
                        searchView.Unfocus();
                        });
                    }
                });
            };