.NET MAUI中如何通过Mopups弹窗返回值？

要实现自定义弹窗关闭后返回值，你可以参考以下两种方式来实现：

方式一：通过ViewModel属性传递结果 #

1. 自定义弹窗ViewModel #

在弹窗的ViewModel中添加结果存储属性，以及触发弹窗关闭的命令：

public class ConfirmationPopupViewModel : ObservableObject
{
    private readonly IPopupNavigation _popupNavigation;
    public ICommand ConfirmCommand { get; }
    public ICommand CancelCommand { get; }
    
    // 用于存储弹窗返回结果
    public bool? Result { get; private set; }

    public ConfirmationPopupViewModel(IPopupNavigation popupNavigation)
    {
        _popupNavigation = popupNavigation;
        ConfirmCommand = new Command(() => ClosePopup(true));
        CancelCommand = new Command(() => ClosePopup(false));
    }

    private void ClosePopup(bool isConfirmed)
    {
        Result = isConfirmed;
        _popupNavigation.PopAsync();
    }
}

2. 弹窗页面绑定命令 #

在弹窗的XAML中，将确认、取消按钮与ViewModel的命令绑定：

<mopups:PopupPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
                  xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
                  xmlns:mopups="clr-namespace:Mopups.Pages;assembly=Mopups"
                  x:Class="YourAppNamespace.ConfirmationPopup"
                  BindingContext="{Binding Source={StaticResource ConfirmationPopupViewModel}}">
    <VerticalStackLayout Padding="20" Spacing="15">
        <Label Text="Do you really want to delete this card?" />
        <HorizontalStackLayout Spacing="10">
            <Button Text="Cancel" Command="{Binding CancelCommand}" />
            <Button Text="OK" Command="{Binding ConfirmCommand}" />
        </HorizontalStackLayout>
    </VerticalStackLayout>
</mopups:PopupPage>

3. 调用弹窗并获取结果 #

在需要弹窗的地方，实例化弹窗和ViewModel，等待弹窗关闭后直接读取ViewModel的结果属性：

var viewModel = new ConfirmationPopupViewModel(popupService);
var confirmationPopup = new ConfirmationPopup { BindingContext = viewModel };

// 显示弹窗，等待关闭
await popupService.PushAsync(confirmationPopup);

// 获取返回结果
bool? isConfirmed = viewModel.Result;
if (isConfirmed == true)
{
    // 执行删除逻辑
}
else
{
    // 取消操作
}

方式二：通过事件回调传递结果 #

适合更复杂的场景，通过ViewModel定义事件，弹窗关闭时触发事件传递结果：

1. 改造ViewModel添加事件 #

public class ConfirmationPopupViewModel : ObservableObject
{
    private readonly IPopupNavigation _popupNavigation;
    public ICommand ConfirmCommand { get; }
    public ICommand CancelCommand { get; }
    
    // 定义弹窗关闭事件
    public event Action<bool>? OnPopupClosed;

    public ConfirmationPopupViewModel(IPopupNavigation popupNavigation)
    {
        _popupNavigation = popupNavigation;
        ConfirmCommand = new Command(() => ClosePopup(true));
        CancelCommand = new Command(() => ClosePopup(false));
    }

    private void ClosePopup(bool isConfirmed)
    {
        OnPopupClosed?.Invoke(isConfirmed);
        _popupNavigation.PopAsync();
    }
}

2. 调用方订阅事件获取结果 #

var viewModel = new ConfirmationPopupViewModel(popupService);
// 订阅事件获取结果
viewModel.OnPopupClosed += (isConfirmed) =>
{
    if (isConfirmed)
    {
        // 处理确认逻辑
    }
};
var confirmationPopup = new ConfirmationPopup { BindingContext = viewModel };
await popupService.PushAsync(confirmationPopup);

内容的提问来源于stack exchange，提问作者Tanaka Mawere