Xamarin.iOS - 如何使用图像实现简单网格

Question

我需要实现一个UIViewController，其中包含一个包含动态列和动态行的网格。我正在编辑this示例，但它是一个带图像的圆圈。

我认为我必须编辑以下文件：

using System;
using System.Collections.Generic;
using CoreGraphics;
using Foundation;
using CoreAnimation;
using UIKit;

namespace SimpleCollectionView
{
public class CircleLayout : UICollectionViewLayout
{
    const float ItemSize = 70.0f;
    int cellCount = 20;
    float radius;
    CGPoint center;

    static NSString myDecorationViewId = new NSString ("MyDecorationView");

    public CircleLayout ()
    {
        RegisterClassForDecorationView (typeof(MyDecorationView), myDecorationViewId);
    }

    public override void PrepareLayout ()
    {
        base.PrepareLayout ();

        CGSize size = CollectionView.Frame.Size;
        cellCount = (int)CollectionView.NumberOfItemsInSection (0);
        center = new CGPoint (size.Width / 2.0f, size.Height / 2.0f);
        radius = (float)Math.Min (size.Width, size.Height) / 2.5f;
    }

    public override CGSize CollectionViewContentSize {
        get {
            return CollectionView.Frame.Size;
        }
    }

    public override bool ShouldInvalidateLayoutForBoundsChange (CGRect newBounds)
    {
        return true;
    }

    public override UICollectionViewLayoutAttributes LayoutAttributesForItem (NSIndexPath path)
    {
        UICollectionViewLayoutAttributes attributes = UICollectionViewLayoutAttributes.CreateForCell (path);
        attributes.Size = new CGSize (ItemSize, ItemSize);
        attributes.Center = new CGPoint (center.X + radius * (float)Math.Cos (2 * path.Row * Math.PI / cellCount),
                                        center.Y + radius * (float)Math.Sin (2 * path.Row * Math.PI / cellCount));
        return attributes;
    }

    public override UICollectionViewLayoutAttributes[] LayoutAttributesForElementsInRect (CGRect rect)
    {
        var attributes = new UICollectionViewLayoutAttributes [cellCount + 1];

        for (int i = 0; i < cellCount; i++) {
            NSIndexPath indexPath = NSIndexPath.FromItemSection (i, 0);
            attributes [i] = LayoutAttributesForItem (indexPath);
        }

        var decorationAttribs = UICollectionViewLayoutAttributes.CreateForDecorationView (myDecorationViewId, NSIndexPath.FromItemSection (0, 0));
        decorationAttribs.Size = CollectionView.Frame.Size;
        decorationAttribs.Center = CollectionView.Center;
        decorationAttribs.ZIndex = -1;
        attributes [cellCount] = decorationAttribs;

        return attributes;
    }

}

public class MyDecorationView : UICollectionReusableView
{
    [Export ("initWithFrame:")]
    public MyDecorationView (CGRect frame) : base (frame)
    {
        BackgroundColor = UIColor.Red;
    }
}
}

但是，我真的不知道我要修改什么来获得一个包含行和列的简单图像网格。

我没有找到任何真实的例子，所以也许有人可以帮我找到一个有用的例子。