Return 从 DialogFragment 到调用的数据 activity

Question

我有一个正在工作的 DialogFragment，需要 return 从微调器中选择的项目。我已经尝试了很多在 Stack Overflow 和其他地方找到的方法，但它们都使用 java，这（显然）不能很好地转换为 Xamarin 中的 c# for Visual Studio 2017。迄今为止，没有任何效果我的 DialogFragment 布局是：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"  
    android:minWidth="300dp" 
    android:minHeight="75dp">
    <TextView
        android:text="Select the department you are registering for."
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAlignment="center" 
        android:textStyle="bold"
        android:id="@+id/textView2" />
    <Spinner
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAlignment="center"
        android:id="@+id/department_spinner" />
    <Button
        android:text="Ok"
        android:layout_width="200px"
        android:layout_gravity="center"
        android:layout_height="34.5dp"
        android:id="@+id/button_ok" />
</LinearLayout>

class代码是：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;

namespace MyProject
{
    class selectDepartment : DialogFragment
    {
        static Spinner department;
        public string selection = "";

        public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
        {
            base.OnCreateView(inflater, container, savedInstanceState);
            View view = inflater.Inflate(Resource.Layout.selectDepartment, container, false);

            Button ok = view.FindViewById<Button>(Resource.Id.button_ok);
            department = view.FindViewById<Spinner>(Resource.Id.department_spinner);

            List<string> list = new List<string>();
            list.Add("Select Department");
            list.Add("Dept. A");
            list.Add("Dept. B");

            var adapter = new ArrayAdapter<string>(this.Activity, Android.Resource.Layout.SimpleSpinnerItem, list.ToArray());
            department.Adapter = adapter;

            ok.Click += (sender, args) =>
            {
                selection = string.Format("{0}", department.GetItemAtPosition(department.SelectedItemPosition));
            };
            return view;
        }

    }
}

这是显示对话框的代码：

            FragmentTransaction getdepartment = FragmentManager.BeginTransaction();
            selectDepartment getDept = new selectDepartment();
            getDept.Show(getdepartment , "Select Department");

            // Here I attempt to read a property which contains the selection
            string selection = getDept.selection;

在我最后一次尝试中，我将微调器选择分配给了属性并且我尝试读取该属性以获取选定的值，但是对话框（显然）显示在不同的线程，并且在执行该行代码时未选择选择。我试着让我的方法 async 和 await 成为对话框，但这只会让事情变得更糟。我错过了什么？

Answer 1

使用 custom event

public class DialogEventArgs : EventArgs
{
    public string Selection { get; set; }
}

然后在 selectDepartment 添加：

public delegate void DialogEventHandler(object sender, DialogEventArgs args);

public event DialogEventHandler Dismissed;

最后在按钮的点击处理程序中添加：

if (null != Dismissed)
    Dismissed(this, new DialogEventArgs { Selection = selection });

创建对话框时，附加事件处理程序

selectDepartment getDept = new selectDepartment();
getDept.Dismissed += (s, e) => { /* do something with e.Selection here */ };

Return 从 DialogFragment 到调用的数据 activity

Return data from DialogFragment to calling activity

c#

xamarin

visual-studio-2017