如何编写返回 xaml 切换开关的值的方法？

Question

I have two xaml toggles in separate files that I want to update simultaneously (if one is switched on the other should be too (and vice versa). My first switch in xaml is:

<Switch Grid.Column="1" x:Name="toggleSwitch1" IsToggled="true" Toggled="OnToggled"/>

Using C# how can I return a boolean value of this switch so that I can update another switch simultaneously? Then once retrieving the value, how can I update the xaml of the toggle status for the other switch?

Answer 1

Your Switch control means, as I can understand, that you using UWP, but I'm not sure.

Anyway, the idea is to bind both controls IsToggled properties to same property of some ViewModel :

using System.ComponentModel;
using System.Runtime.CompilerServices;

namespace MyWPFApp
{
    public class ControlsViewModel : INotifyPropertyChanged
    {
        private bool switchToggled;
        public bool SwitchToggled
        {
            get => switchToggled;
            set
            {
                switchToggled = value;
                OnPropertyChanged(nameof(SwitchToggled));
            }
        }

        public ControlsViewModel() { }

        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged([CallerMemberName]string propertyName = "") => 
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

Then in XAML of both Window s set bindings to Switch control (in my example - CheckBox control):

<!-- Window 1 -->
<Window x:Class="MyWPFApp.Window1"
        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:MyWPFApp"
        mc:Ignorable="d"
        Title="Window 1" Height="100" Width="300">
    <Grid>
        <CheckBox Content="Window1 CheckBox"
                  IsChecked="{Binding SwitchToggled}"/>
                  <!-- Replace IsChecked to IsToggled property -->
    </Grid>
</Window>

<!-- Window 2 -->
<Window x:Class="MyWPFApp.Window2"
        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:MyWPFApp"
        mc:Ignorable="d"
        Title="Window 2" Height="100" Width="300">
    <Grid>
        <CheckBox Content="Window2 CheckBox" 
                  IsChecked="{Binding SwitchToggled}"/>
                  <!-- Replace IsChecked to IsToggled property -->
    </Grid>
</Window>

Code-behind of both Window s in example is same:

using System.Windows;

namespace MyWPFApp
{
    public partial class Window1 : Window // or public partial class Window2
    {
        public Window1(ControlsViewModel cvm) // or public Window2
        {
            InitializeComponent();
            DataContext = cvm;
        }
    }
}

And when calling that example Window s to show from Main one, you creating ControlsViewModel instance and pass it to both:

using System.Windows;

namespace MyWPFApp
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            var cvm = new ControlsViewModel();

            new Window1(cvm).Show();
            new Window2(cvm).Show();
        }
    }
}

So checking/unchecking (toggle/untoggle) one of them will affect another and vice versa. Also, you can change SwitchToggled from code somewhere, which would affect both controls too.

Please note, that this is just example to try explain the idea. More MVVM pattern explanations and examples you can find at MSDN .