UWP MVVM NavigationView BackButton -按下时检测

<NavigationView
    x:Name="navigationView"
    IsBackButtonVisible="Visible"
    BackRequested="NavigationView_BackRequested">
    <!-- 其他内容 -->
</NavigationView>

public sealed partial class MainPage : Page
{
    public MainPage()
    {
        this.InitializeComponent();
        this.DataContext = new MainViewModel();
    }

    private void NavigationView_BackRequested(NavigationView sender, NavigationViewBackRequestedEventArgs args)
    {
        var viewModel = DataContext as MainViewModel;
        viewModel?.BackCommand.Execute(null);
    }
}

using System.Windows.Input;
using Windows.UI.Xaml.Navigation;

public class MainViewModel : ViewModelBase
{
    public ICommand BackCommand { get; }

    public MainViewModel()
    {
        BackCommand = new RelayCommand(OnBackRequested);
    }

    private void OnBackRequested()
    {
        // 实现后退逻辑，例如导航到上一个页面
        if (Frame.CanGoBack)
        {
            Frame.GoBack();
        }
    }

    private Frame Frame => (Frame)Windows.UI.Xaml.Window.Current.Content;
}

using System;
using System.Windows.Input;

public class RelayCommand : ICommand
{
    private readonly Action _execute;
    private readonly Func<bool> _canExecute;

    public RelayCommand(Action execute, Func<bool> canExecute = null)
    {
        _execute = execute ?? throw new ArgumentNullException(nameof(execute));
        _canExecute = canExecute;
    }

    public event EventHandler CanExecuteChanged;

    public bool CanExecute(object parameter)
    {
        return _canExecute == null || _canExecute();
    }

    public void Execute(object parameter)
    {
        _execute();
    }

    public void RaiseCanExecuteChanged()
    {
        CanExecuteChanged?.Invoke(this, EventArgs.Empty);
    }
}