如何在 iOS Xamarin.Forms 中禁用幻灯片菜单功能

Question

我在 Masterdetail 页面中的幻灯片菜单遇到了一些问题。我想禁用 iOS 中的功能。

在Android，我可以禁用。但是，在 iOS 中它不起作用。

"IsGestureEnabled="False" - 此属性在 Android 中运行。但在 iOS 中没有。

请帮我解决这个问题。

Answer 1

它似乎已经存在，您可以使用 CustomRenderer 。这是workaround。但是，由于 Xamarin 的更新，此解决方法似乎已过时。所以我们可以改进它。

[assembly: ExportRenderer (typeof(MasterDetailPage), typeof(ExtendedMasterDetailPageRenderer), UIUserInterfaceIdiom.Phone)]
namespace Core.iOS.Renderers
{
    public class ExtendedMasterDetailPageRenderer : PhoneMasterDetailRenderer
    {
        private MasterDetailPage page;

        public ExtendedMasterDetailPageRenderer ()
        {

        }

         // add following override method
        public override void ViewDidLayoutSubviews()
        {
          base.ViewDidLayoutSubviews();
          ((MasterDetailPage)this.Element).PropertyChanged += HandlePropertyChanged;
        }
        
        public override void ViewDidLoad ()
        {
            base.ViewDidLoad ();

            ((MasterDetailPage)this.Element).PropertyChanged += HandlePropertyChanged;
        }

        private void HandlePropertyChanged (object sender, PropertyChangedEventArgs e)
        {
            if (e.PropertyName == MasterDetailPage.IsGestureEnabledProperty.PropertyName)
            {
                var panGesture = typeof(PhoneMasterDetailRenderer).GetField ("panGesture", BindingFlags.NonPublic | BindingFlags.Instance).GetValue (this) as UIPanGestureRecognizer;
                var hasPanGesture = false;

                if (panGesture != null)
                {
                    for (int i = 0; i < this.View.GestureRecognizers.Length; i++)
                    {
                        if (this.View.GestureRecognizers [i] is UIPanGestureRecognizer)
                        {
                            hasPanGesture = true;
                            break;
                        }
                    }

                    if (((MasterDetailPage)this.Element).IsGestureEnabled)
                    {
                        if (!hasPanGesture)
                        {
                            this.View.AddGestureRecognizer (panGesture);
                        }
                        return;
                    }

                    if (hasPanGesture)
                    {
                        this.View.RemoveGestureRecognizer (panGesture);
                    }
                }
            }
        }
    }
}

在你的 MasterDetailPage

protected override void OnAppearing()
{
   base.OnAppearing();

   IsGestureEnabled = false;
}

更新

创建CustomRenderer 的Page

[assembly: ExportRenderer(typeof(Page), typeof(MyPageRenderer), UIUserInterfaceIdiom.Phone)]
namespace xxx.iOS
{
    class MyPageRenderer : PageRenderer
    {
        public override void ViewDidLayoutSubviews()
        {
            base.ViewDidLayoutSubviews();
            if (this.NavigationController != null)
            {
                var items = this.NavigationController.NavigationBar.Items;
                if(items.Length > 0)
                {
                    UIBarButtonItem leftItem = items[0].LeftBarButtonItem;
                    if(this.NavigationController.ViewControllers.Length == 1)
                    {
                        leftItem.Enabled = false;
                    }                   
                }
            }
        }
    }
}