.NET MAUI：打开FlyoutPage时自动隐藏键盘的实现需求

核心思路 #

监听FlyoutPage的IsPresented属性状态，当属性切换为true（侧边栏展开）时，强制隐藏当前页面的软键盘。

实现方案 #

方案一：直接在FlyoutPage后台代码处理

在你的FlyoutPage的.xaml.cs文件中添加属性变更监听，触发键盘隐藏逻辑：

public partial class MainFlyoutPage : FlyoutPage
{
    public MainFlyoutPage()
    {
        InitializeComponent();
        PropertyChanged += MainFlyoutPage_PropertyChanged;
    }

    private void MainFlyoutPage_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
    {
        if (e.PropertyName == nameof(IsPresented) && IsPresented)
        {
            HideSoftKeyboard();
        }
    }

    private void HideSoftKeyboard()
    {
        // 分平台实现键盘隐藏
#if ANDROID
        var inputMethodManager = Android.App.Application.Context.GetSystemService(Android.Content.Context.InputMethodService) as Android.Views.InputMethods.InputMethodManager;
        var currentFocus = Android.App.Application.Context.CurrentActivity?.CurrentFocus;
        if (currentFocus != null)
        {
            inputMethodManager.HideSoftInputFromWindow(currentFocus.WindowToken, 0);
            currentFocus.ClearFocus();
        }
#elif IOS
        UIKit.UIApplication.SharedApplication.KeyWindow?.EndEditing(true);
#elif WINDOWS
        Microsoft.UI.Xaml.Window.Current.CoreWindow.PointerCursor = new Windows.UI.Core.CoreCursor(Windows.UI.Core.CoreCursorType.Arrow, 0);
        Microsoft.UI.Xaml.Input.FocusManager.TryMoveFocus(Microsoft.UI.Xaml.Input.FocusNavigationDirection.Next);
#endif
    }
}

方案二：用Behavior实现解耦复用

如果希望页面代码更简洁，可封装成Behavior组件：

public class HideKeyboardOnFlyoutOpenBehavior : Behavior<FlyoutPage>
{
    protected override void OnAttachedTo(FlyoutPage bindable)
    {
        base.OnAttachedTo(bindable);
        bindable.PropertyChanged += Bindable_PropertyChanged;
    }

    protected override void OnDetachingFrom(FlyoutPage bindable)
    {
        base.OnDetachingFrom(bindable);
        bindable.PropertyChanged -= Bindable_PropertyChanged;
    }

    private void Bindable_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
    {
        var flyoutPage = sender as FlyoutPage;
        if (e.PropertyName == nameof(FlyoutPage.IsPresented) && flyoutPage.IsPresented)
        {
            HideSoftKeyboard();
        }
    }

    private void HideSoftKeyboard()
    {
        // 同方案一的平台键盘隐藏逻辑
#if ANDROID
        var inputMethodManager = Android.App.Application.Context.GetSystemService(Android.Content.Context.InputMethodService) as Android.Views.InputMethods.InputMethodManager;
        var currentFocus = Android.App.Application.Context.CurrentActivity?.CurrentFocus;
        if (currentFocus != null)
        {
            inputMethodManager.HideSoftInputFromWindow(currentFocus.WindowToken, 0);
            currentFocus.ClearFocus();
        }
#elif IOS
        UIKit.UIApplication.SharedApplication.KeyWindow?.EndEditing(true);
#elif WINDOWS
        Microsoft.UI.Xaml.Window.Current.CoreWindow.PointerCursor = new Windows.UI.Core.CoreCursor(Windows.UI.Core.CoreCursorType.Arrow, 0);
        Microsoft.UI.Xaml.Input.FocusManager.TryMoveFocus(Microsoft.UI.Xaml.Input.FocusNavigationDirection.Next);
#endif
    }
}

然后在XAML中引用该Behavior：

<FlyoutPage ...>
    <FlyoutPage.Behaviors>
        <local:HideKeyboardOnFlyoutOpenBehavior />
    </FlyoutPage.Behaviors>
    <!-- 页面其余内容 -->
</FlyoutPage>

注意事项 #

• Android平台额外清除了当前控件焦点，避免Entry重新获取焦点后再次弹出键盘
• 所有平台逻辑均为原生API调用，无第三方依赖，兼容性稳定

内容的提问来源于stack exchange，提问作者Dryzler