废话不说，直接上代码

using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Markup;

namespace L2_Core_LoadXaml
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public class VM : INotifyPropertyChanged
        {
            public event PropertyChangedEventHandler PropertyChanged;

            public void RaisePropertyChanged([CallerMemberName]  string propertyName = "")
            {
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
            }
            private string _A;
            public string A
            {
                get => _A;
                set
                {
                    _A = value;
                    RaisePropertyChanged();
                }
            }
        }
        public MainWindow()
        {
            InitializeComponent();
            this.DataContext = new VM() { A = "Hello" };
            this.Loaded += MainWindow_Loaded;
        }

        private void MainWindow_Loaded(object sender, RoutedEventArgs e)
        {
            string xaml = @"
<Grid xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation"">
    <Button  Name=""Button1"" Content=""{Binding A}""></Button>
</Grid >
";

            var rootElement = (DependencyObject)XamlReader.Parse(xaml);
            this.Content = rootElement;
            Button button1 = (Button)LogicalTreeHelper.FindLogicalNode(rootElement, "Button1");
            button1.Click += (o, e) => MessageBox.Show("Xaml loaded!");
        }
    }
}

有了这玩意，似乎打开了一扇窗——前后端真正分离？

[Wpf学习] 2.代码导入Xaml