Listview 如何在母版详细信息页中设置列表视图的默认选定项

我正在引用Xamarin Master Detail示例应用程序。在这种情况下，我们在母版详细信息页面中使用ListView。我们希望在启动MasterDetailPage时将第一项设置为选中项

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我发现处理此问题的最佳方法是停止依赖内置的

列表视图

选择样式，并自行处理选择的背景更改。不幸的是，禁用默认选择样式需要自定义渲染

实现下面的

ViewCell

渲染器以禁用默认选择样式。然后，您只需将您的

ViewCell

子控件的

BackgroundColor

绑定到模型上的

IsSelected

属性，或者以您想要的方式进行绑定

要设置默认选定项目时：

mySelectedItem.IsSelected = true; //Assuming this bubbles up a PropertyChanged event to the ListView

MyListView.SelectedItem = mySelectedItem;
// Maybes scroll to the item here if necessary

下面的代码并不完美，所以请告诉我是否可以进行任何改进

Xamarin形成ViewCell

public class CustomViewCell : ViewCell { }

Android ViewCell自定义渲染器

public class CustomViewCellRenderer : ViewCellRenderer {

    protected override View GetCellCore(Cell item, View convertView, ViewGroup parent, Context context) {
        View cellCore = base.GetCellCore(item, convertView, parent, context);

        if(parent is ListView listView) {
            listView.SetSelector(Android.Resource.Color.Transparent);
            listView.CacheColorHint = Color.White;
        }

        cellCore.SetBackground(GetUnpressedBackground());

        return cellCore;
    }


    private StateListDrawable GetUnpressedBackground() {
        StateListDrawable states = new StateListDrawable();
        //states.AddState(new[] { Android.Resource.Attribute.StatePressed }, new ColorDrawable(Color.White));
        //states.AddState(new[] { Android.Resource.Attribute.StateFocused }, new ColorDrawable(Color.White));
        //states.AddState(new int[] { }, new ColorDrawable(Color.Blue.ToAndroid()));

        return states;
    }
}

public class CustomViewCellRenderer : ViewCellRenderer {

    public override UITableViewCell GetCell(Cell item, UITableViewCell reusableCell, UITableView tv) {
        UITableViewCell  cell = base.GetCell(item, reusableCell, tv);

        if(cell != null) {
            // Disable native cell selection color style - set as *Transparent*
            cell.SelectionStyle = UITableViewCellSelectionStyle.None;

            //cell.SelectedBackgroundView = new UIView(new RectangleF(0, 0, (float)cell.Bounds.Width, (float)cell.Bounds.Height)) {
            //    BackgroundColor = UIColor.Clear
            //};
        }

        return cell;
    }
}

iOS ViewCell自定义渲染器

public class CustomViewCellRenderer : ViewCellRenderer {

    protected override View GetCellCore(Cell item, View convertView, ViewGroup parent, Context context) {
        View cellCore = base.GetCellCore(item, convertView, parent, context);

        if(parent is ListView listView) {
            listView.SetSelector(Android.Resource.Color.Transparent);
            listView.CacheColorHint = Color.White;
        }

        cellCore.SetBackground(GetUnpressedBackground());

        return cellCore;
    }


    private StateListDrawable GetUnpressedBackground() {
        StateListDrawable states = new StateListDrawable();
        //states.AddState(new[] { Android.Resource.Attribute.StatePressed }, new ColorDrawable(Color.White));
        //states.AddState(new[] { Android.Resource.Attribute.StateFocused }, new ColorDrawable(Color.White));
        //states.AddState(new int[] { }, new ColorDrawable(Color.Blue.ToAndroid()));

        return states;
    }
}

public class CustomViewCellRenderer : ViewCellRenderer {

    public override UITableViewCell GetCell(Cell item, UITableViewCell reusableCell, UITableView tv) {
        UITableViewCell  cell = base.GetCell(item, reusableCell, tv);

        if(cell != null) {
            // Disable native cell selection color style - set as *Transparent*
            cell.SelectionStyle = UITableViewCellSelectionStyle.None;

            //cell.SelectedBackgroundView = new UIView(new RectangleF(0, 0, (float)cell.Bounds.Width, (float)cell.Bounds.Height)) {
            //    BackgroundColor = UIColor.Clear
            //};
        }

        return cell;
    }
}

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到目前为止你尝试了什么？您可以设置SelectedItem属性。@Depechie:我尝试使用Selected Item属性，但菜单项没有突出显示。您可以使用文件设置默认的选定页面。在这个示例中，他们将联系人页面设置为选中状态。我们正在与UWP合作。其中我们需要在Xamarin.Forms中设置默认项。@AnkitJain查找UWP ViewCell渲染器（如果UWP上需要），然后按照上面的说明进行操作。