flower-story/FlowerApp/Platforms/iOS/Controls/MauiWaterfallLayout.cs

using Blahblah.FlowerApp.Controls;
using Foundation;
using UIKit;

namespace Blahblah.FlowerApp.Platforms.iOS.Controls;

public class MauiWaterfallLayout : UIView, IUICollectionViewDataSource, IUICollectionViewDelegate
{
    WaterfallLayout? layout;
    UICollectionView? collectionView;

    public MauiWaterfallLayout(WaterfallLayout layout)
    {
        this.layout = layout;

        var flow = new FlowLayout(layout.Columns)
        {
            //CalculateCellHeight = 
            MinimumInteritemSpacing = 12f,
            SectionInset = new UIEdgeInsets(12f, 12f, 12f, 12f)
        };

        var refreshControl = new UIRefreshControl
        {
            TintColor = UIColor.SystemFill
        };
        refreshControl.ValueChanged += (sender, e) =>
        {
            if (sender is UIRefreshControl control)
            {
                control.EndRefreshing();
            }
        };

        collectionView = new UICollectionView(Bounds, flow)
        {
            DataSource = this,
            Delegate = this,
            RefreshControl = refreshControl,
            TranslatesAutoresizingMaskIntoConstraints = false
        };
        AddSubview(collectionView);

        var safe = SafeAreaLayoutGuide;
        AddConstraints(new[]
        {
            NSLayoutConstraint.Create(collectionView, NSLayoutAttribute.Leading, NSLayoutRelation.Equal, safe, NSLayoutAttribute.Leading, 1f, 0f),
            NSLayoutConstraint.Create(collectionView, NSLayoutAttribute.Trailing, NSLayoutRelation.Equal, safe, NSLayoutAttribute.Trailing, 1f, 0f),
            NSLayoutConstraint.Create(collectionView, NSLayoutAttribute.Top, NSLayoutRelation.Equal, safe, NSLayoutAttribute.Top, 1f, 0f),
            NSLayoutConstraint.Create(collectionView, NSLayoutAttribute.Bottom, NSLayoutRelation.Equal, safe, NSLayoutAttribute.Bottom, 1f, 0f),
        });
    }

    public UICollectionViewCell GetCell(UICollectionView collectionView, NSIndexPath indexPath)
    {
        return new UICollectionViewCell();
    }

    public nint GetItemsCount(UICollectionView collectionView, nint section)
    {
        return 5;
    }

    public void UpdateColumns()
    {
        if (layout != null && collectionView?.CollectionViewLayout is FlowLayout flow)
        {
            flow.SetCols(layout.Columns);
        }
    }

    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            if (collectionView != null)
            {
                collectionView.Dispose();
                collectionView = null;
            }
            layout = null;
        }

        base.Dispose(disposing);
    }
}