双向绑定

1. xaml

<Window x:Class="WpfApp2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp2"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Window.Resources>
        <Style TargetType="Grid">
            <Setter Property="Background" Value="Aqua"></Setter>

        </Style>
    </Window.Resources>
    <Grid Margin="100">
        <TextBox Text="{Binding MyProperty ,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" Height="30"></TextBox>
        <TextBlock Text="{Binding MyProperty}" Width="100" Height="30"></TextBlock>
    </Grid>
</Window>

2. cs后台

namespace WpfApp2
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public string text { get; set; }
        private MyViewModel myView = new MyViewModel();
        public MainWindow()
        {
            InitializeComponent();
            text = "ab";
            this.DataContext =myView;
        }
    }
}

3. ViewModel

namespace WpfApp2
{
    public class MyViewModel:INotifyPropertyChanged
    {
        private string _myProperty;
        public string MyProperty
        {
            get { return _myProperty; }
            set
            {
                if (_myProperty != value)
                {
                    _myProperty = value;
                    OnPropertyChanged(nameof(MyProperty));
                }
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged(string propertyName)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}