在Xamarin Native中具有节布局问题的UICollectionView

Question

我有8个部分的UIcollectionView。每个部分都有一个专用数组作为数据源。我想在按钮上的每个部分添加一个项目。 UICollectionView滚动方向设置为“水平”，因为我希望这些部分为垂直方向。在此屏幕快照中，一切都在Xcode项目（Xib和Objective-C）中正常工作（红色项目是按钮按下时添加的项目）。

当我在Xamarin ios中执行相同的实现时，按下面的按钮后布局变得一团糟。

我的代码如下

 public partial class GridViewController : UIViewController
{
    CVSource source;

    int MAX_NUMBER_OF_ROWS = 4;

    public GridViewController(IntPtr handle) : base(handle)
    {
    }

    public override void ViewDidLoad()
    {
        base.ViewDidLoad();
        // Perform any additional setup after loading the view, typically from a nib.
        //this.collectionView.SetNeedsDisplay();
        this.collectionView.RegisterClassForCell(typeof(ItemCell), ItemCell.CellId);

        source = new CVSource();
        this.collectionView.DataSource = source;


    }

    partial void AddButtonPressed(UIButton sender)
    {
        Console.WriteLine("Add button pressed");

        MAX_NUMBER_OF_ROWS = MAX_NUMBER_OF_ROWS + 1;
        source.AddItem();

        collectionView.Layer.RemoveAllAnimations();
        collectionView.ReloadData();

        ViewDidLayoutSubviews();

    }

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

        collectionView.Frame = new CoreGraphics.CGRect(collectionView.Frame.Location.X, collectionView.Frame.Location.Y, collectionView.Frame.Size.Width, MAX_NUMBER_OF_ROWS * 40);
        btnAdd.Frame = new CoreGraphics.CGRect(btnAdd.Frame.Location.X, collectionView.Frame.Location.Y + collectionView.Frame.Size.Height + 10, btnAdd.Frame.Size.Width, btnAdd.Frame.Size.Height);

    }

    public override void DidReceiveMemoryWarning()
    {
        base.DidReceiveMemoryWarning();
        // Release any cached data, images, etc that aren't in use.
    }

DataSource类

class CVSource : UICollectionViewSource
{

    List<string> arr1 = new List<string> { "40", "30"};
    List<string> arr2 = new List<string> { "25", "22" };
    List<string> arr3 = new List<string> { "35", "67" };
    List<string> arr4 = new List<string> { "26", "12" };
    List<string> arr5 = new List<string> { "27", "21", };
    List<string> arr6 = new List<string> { "12", "45" };
    List<string> arr7 = new List<string> { "34", "67" };
    List<string> arr8 = new List<string> { "21", "44", };


    public override nint NumberOfSections(UICollectionView collectionView)
    {
        return 8;
    }

    public override nint GetItemsCount(UICollectionView collectionView, nint section)
    {
        if ((int)section == 0)
            return arr1.Count;
        else if ((int)section == 1)
            return arr2.Count;
        else if ((int)section == 2)
            return arr3.Count;
        else if ((int)section == 3)
            return arr4.Count;
        else if ((int)section == 4)
            return arr5.Count;
        else if ((int)section == 5)
            return arr6.Count;
        else if ((int)section == 6)
            return arr7.Count;
        else if ((int)section == 7)
        return arr8.Count;

        return 0;
    }



    public override UICollectionViewCell GetCell(UICollectionView collectionView, Foundation.NSIndexPath indexPath)
    {
        var itemCell = (ItemCell)collectionView.DequeueReusableCell(ItemCell.CellId, indexPath);

        if (indexPath.Section == 0)
        {
            itemCell.SetText(arr1[indexPath.Row]);

        }
        else if (indexPath.Section == 1)
        {
            itemCell.SetText(arr2[indexPath.Row]);

        }
        else if (indexPath.Section == 2)
        {
            itemCell.SetText(arr3[indexPath.Row]);

        }
        else if (indexPath.Section == 3)
        {
            itemCell.SetText(arr4[indexPath.Row]);

        }
        else if (indexPath.Section == 4)
        {
            itemCell.SetText(arr5[indexPath.Row]);

        }
        else if (indexPath.Section == 5)
        {
            itemCell.SetText(arr6[indexPath.Row]);

        }
        else if (indexPath.Section == 6)
        {
            itemCell.SetText(arr7[indexPath.Row]);

        }
        else if (indexPath.Section == 7)
            itemCell.SetText(arr8[(indexPath.Row)]);


        return itemCell;
    }

    public override void ItemSelected(UICollectionView collectionView, NSIndexPath indexPath)
    {
        Console.WriteLine("Row selected "+ indexPath.Row);
    }


    public void AddItem()
    {
        arr1.Add("0");
        arr2.Add("0");
        arr3.Add("0");
        arr4.Add("0");
        arr5.Add("0");
        arr6.Add("0");
        arr7.Add("0");
        arr8.Add("0");

    }
}

我不是Xamarin开发人员，感谢Xamarin专家的任何评论/建议

Answer 1

也许您错过了为collectionView设置的UICollectionViewLayout，可以将collectionView的GridLayout设置为尝试一下。

this.collectionView.SetCollectionViewLayout(new GridLayout(), true); //add CollectionViewLayout
this.collectionView.RegisterClassForCell(typeof(ItemCell), ItemCell.CellId);

GridLayout继承自Xamrarin iOS中的UICollectionViewFlowLayout：

public class GridLayout : UICollectionViewFlowLayout
{
    public GridLayout ()
    {
    }

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

    public override UICollectionViewLayoutAttributes LayoutAttributesForItem (NSIndexPath path)
    {
        return base.LayoutAttributesForItem (path);
    }

    public override UICollectionViewLayoutAttributes[] LayoutAttributesForElementsInRect (CGRect rect)
    {
        return base.LayoutAttributesForElementsInRect (rect);
    }
}

效果：

之后尝试共享代码，效果如下：