Xamarin.Forms Android DatePicker/TimePicker button listener

Question

I need to know if a user tapped on the Cancel or Ok button in a Date/Time picker of an xamarin.Forms Android app.

I have tried to add a function to the Click event but this is never triggered.

This is my code (similar for the TimePicker):

using Android.Content;
using MyApp.Droid;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
using MyApp.Models;
using Java.Util;

[assembly: ExportRenderer(typeof(DatePicker), typeof(DatePickerCustomRenderer))]

namespace MyApp.Droid {
    public class DatePickerCustomRenderer : DatePickerRenderer {

        public DatePickerCustomRenderer(Context context) : base(context) { } 

        protected override void OnElementChanged(ElementChangedEventArgs<DatePicker> e) {
            base.OnElementChanged(e);

            Locale locale = new Locale(Utente.FormatoPerDateTimePicker);
            Control.TextLocale = locale;

            Control.Click += Control_Click;
        }

        private void Control_Click(object sender, System.EventArgs e) {
            // This function is never called :(
            throw new System.NotImplementedException();
        }
    }
}

How can I do this?

Answer 1

Using the following Android DatePicker custom renderer you have total control over OK and CANCEL.

using Android.App;
using Android.Content;
using ???.Android.Renderers;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
using DatePicker = Xamarin.Forms.DatePicker;

[assembly: ExportRenderer(typeof(DatePicker), typeof(FixedDatePickerRenderer))]    
namespace ???.Android.Renderers
{
    public class FixedDatePickerRenderer : Xamarin.Forms.Platform.Android.DatePickerRenderer
    {
        public FixedDatePickerRenderer(Context context) : base(context)
        {
        }

        protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.DatePicker> e)
        {
            base.OnElementChanged(e);

            //Disposing
            if (e.OldElement != null)
            {
                _element = null;
            }

            //Creating
            if (e.NewElement != null)
            {
                _element = e.NewElement;
            }
        }

        protected Xamarin.Forms.DatePicker _element;

        protected override DatePickerDialog CreateDatePickerDialog(int year, int month, int day)
        {
            var dialog = new DatePickerDialog(Context, (o, e) =>
            {
                _element.Date = e.Date;
                ((IElementController)_element).SetValueFromRenderer(VisualElement.IsFocusedPropertyKey, false);
            }, year, month, day);

            dialog.SetButton((int)DialogButtonType.Positive, Context.Resources.GetString(global::Android.Resource.String.Ok), OnOk);
            dialog.SetButton((int)DialogButtonType.Negative, Context.Resources.GetString(global::Android.Resource.String.Cancel), OnCancel);

            return dialog;
        }

        private void OnCancel(object sender, DialogClickEventArgs e)
        {
            _element.Unfocus();
            //((FixedDatePicker) _element)?.CallOnCancel();
        }
        private void OnOk(object sender, DialogClickEventArgs e)
        {
            //need to set date from native control manually now
            _element.Date = ((DatePickerDialog)sender).DatePicker.DateTime;
            _element.Unfocus();
            //((FixedDatePicker)_element)?.CallOnOk();
        }

    }

}


 

Just for people looking for a complete solution to avoid searching for iOS, there's an option already included out-of-the box: https://learn.microsoft.com/en-us/xamarin/xamarin-forms/platform/ios/datepicker-selection

Answer 2

I need to know if a user tapped on the "cancel" or on the "ok" button in a date/time picker of an xamarin.Forms Android app.

With Xamarin.Form's DatePicker , you can't do that. Xamarin.Forms.DatePicker is renderered into an EditText control. The pop up DatePickerDialog is unfortunately not exposed to user. You can see that from Source Codes of DatePickerRenderer .

So if you really want to detect the OK/Cancel button click events. You need to implement your own DatePickerRenderer according to the source codes.

Answer 3

Nick Kovalsky' solution (using a custom renderer) above for Android works fine for me.

For iOS, the iOS specifics out-of-the-box solution didn't work for me, https://learn.microsoft.com/en-us/xamarin/xamarin-forms/platform/ios/datepicker-selection

I've used the custom renderer approach for iOS also, Looking at the Xamarin custom renderer (On iOS platform), we can see the InputAccessoryView is set to UIToolbar , and the toolbar contains the Done button (UIBarButtonItem) . So, we can use the Done button and listen for click event,
https://github.com/xamarin/Xamarin.Forms/blob/master/Xamarin.Forms.Platform.iOS/Renderers/DatePickerRenderer.cs

[assembly: ExportRenderer(typeof(CustomDatePicker), typeof(MyApp.iOS.CustomRenderers.CustomDatePickerRenderer))]
public class CustomDatePickerRenderer : DatePickerRenderer
    {      
        CustomDatePicker _datePickerElement ;

        protected override void OnElementChanged(ElementChangedEventArgs<DatePicker> e)
        {
            base.OnElementChanged(e);

            if (e.NewElement is CustomDatePicker datePickerElement && Control != null)
            {
                _datePickerElement = datePickerElement;                

                var toolbar = Control.InputAccessoryView as UIToolbar;
                foreach (var button in toolbar?.Items)
                {
                    if (button.Style == UIBarButtonItemStyle.Done)
                    {
                        button.Clicked -= OnDoneButtonClicked;
                        button.Clicked += OnDoneButtonClicked;
                    }
                }
            }
        }

        private void OnDoneButtonClicked(object sender, EventArgs e)
        {
            if(_datePickerElement.NullableDate != _datePickerElement.Date)
            {
                _datePickerElement.NullableDate = _datePickerElement.Date;
            }            
        }

    }