在iOS上，CollectionView无法正常工作

Question

我在Xaml中有一个视图，我正在尝试按以下方式使用集合视图

<CollectionView 
x:Name="ColorCollectionView" 
Margin="5" 
HeightRequest="250" 
WidthRequest="250" 
ItemSizingStrategy="MeasureFirstItem" 
ItemsSource="{Binding Categories}" 
SelectedItem="{Binding SelectedCategory, Mode=OneWayToSource}"
SelectionChangedCommand="{Binding SelectedItemChangedCommand}"
SelectionChangedCommandParameter="{Binding Source={x:Reference ColorCollectionView}, Path=SelectedItem}"
SelectionMode="Single" 
VerticalOptions="Center"> 
   <CollectionView.ItemsLayout> 
     <GridItemsLayout Orientation="Horizontal" Span="2"
   </CollectionView.ItemsLayout>
   <CollectionView.ItemTemplate> 
     <DataTemplate> 
         <StackLayout Padding="20,0" Spacing="0">
                <Frame Padding="10" 
                       BackgroundColor="White" 
                       BorderColor="{Binding 
                       BackgroundSelectedColor}" 
                       CornerRadius="100" 
                       HasShadow="False"> 
                 <Image HeightRequest="60" Source="{Binding Image}"WidthRequest="60"/>
                  </Frame>
                  <Label FontFamily="{x:Static constants:Fonts.Medium}" FontSize="12" HorizontalOptions="Center" Text="{Binding Name}" TextColor="Black" /
          </StackLayout>
     </DataTemplate>
  </CollectionView.ItemTemplate>
</CollectionView>

它在android中工作正常，但是我在iOSd中遇到了这个异常

Managed Stacktrace:
at <unknown> <0xffffffff>
at ObjCRuntime.Messaging:nint_objc_msgSend_nint <0x0011f>
at UIKit.UICollectionView:NumberOfItemsInSection <0x0017a>
at Xamarin.Forms.Platform.iOS.GridViewLayout:NeedsPartialColumnAdjustment <0x00282>  at

Xamarin.Forms.Platform.iOS.GridViewLayout：get_CollectionViewContentSize