Xamarin.Forms Android DatePicker/TimePicker 按钮侦听器

Question

我需要知道用户是否点击了取消或确定按钮在 Date/Time 选择器 的 xamarin.Forms Android 应用中。

我曾尝试向 Click 事件添加一个函数，但从未触发过。

这是我的代码（类似于 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();
        }
    }
}

我该怎么做？

Answer 1

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.

对于 Xamarin.Form 的 DatePicker，您不能这样做。 Xamarin.Forms.DatePicker 渲染到 EditText 控件中。不幸的是，弹出窗口 DatePickerDialog 没有暴露给用户。从 Source Codes of DatePickerRenderer.

可以看出

所以如果你真的想检测OK/Cancel按钮点击事件。你需要根据源码实现自己的DatePickerRenderer

Answer 2

使用以下 Android DatePicker 自定义呈现器，您可以完全控制确定和取消。

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();
        }

    }

}

仅供寻求完整解决方案以避免搜索 iOS 的用户使用，其中包含一个开箱即用的选项：https://docs.microsoft.com/en-us/xamarin/xamarin-forms/platform/ios/datepicker-selection

Answer 3

Nick Kovalsky 上面针对 Android 的解决方案（使用自定义渲染器）对我来说效果很好。

对于 iOS，iOS 具体的现成解决方案对我不起作用， https://docs.microsoft.com/en-us/xamarin/xamarin-forms/platform/ios/datepicker-selection

我也为 iOS 使用了自定义渲染器方法，查看 Xamarin 自定义渲染器（在 iOS 平台上），我们可以看到 InputAccessoryView 设置为 UIToolbar，并且工具栏包含完成按钮 (UIBarButtonItem)。所以，我们可以使用完成按钮并监听点击事件，
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;
            }            
        }

    }

Xamarin.Forms Android DatePicker/TimePicker 按钮侦听器

Xamarin.Forms Android DatePicker/TimePicker button listener

c#

android

datepicker

xamarin.forms

timepicker