从集合 vew 单元格中的选定单元格获取数据

Question

I have a functional collection view where I store the employee ID and I need to get that data from the cell when it's selected. I created a UICollectionViewDelegate where I get the index of the selected view in the view collection, but the cell returned does not have the property where I store the employee id. I've looked all over for a solution, but nothing addresses my specific issue and nothing I've tried to date works. My code:

The collection view:

public partial class Participants : UIViewController
{
    public User MyUser;
    public string company = "";
    public string department = "";
    public string section = "";
    public Participants(IntPtr handle) : base(handle)
    {
    }
    public override void ViewDidLoad()
    {
        base.ViewDidLoad();
        DataInterfaceWeb.DataInterface myService = new DataInterfaceWeb.DataInterface();
        DataSet dbParticipants = myService.GetParticipantsWithPhoto(MyUser.Username, MyUser.Password, company, department, section, "CURRENT");

        View.SubviewsDoNotTranslateAutoresizingMaskIntoConstraints();
        var height = this.NavigationController.NavigationBar.Bounds.Height;
        var width = this.NavigationController.NavigationBar.Bounds.Width;

        viewParticipants.AddConstraints(

            banner.AtTopOf(View, height),
            banner.AtRightOf(View, 0),
            banner.AtLeftOf(View, 0),

            lblTitle.Below(banner, 0),
            lblTitle.WithSameWidth(banner)
            , cvParticipants.Below(lblTitle, 0),
            cvParticipants.WithSameWidth(lblTitle),
            cvParticipants.AtLeftOf(View, 10),
            cvParticipants.AtRightOf(View, 10),
            cvParticipants.AtBottomOf(View,10)
        );

        cvParticipants.CollectionViewLayout = new UICollectionViewFlowLayout()
        {
            ItemSize = new CGSize((float)UIScreen.MainScreen.Bounds.Size.Width / 2.15f, (float)UIScreen.MainScreen.Bounds.Size.Width / 2.15f),
            HeaderReferenceSize = new CGSize(25, 25),
            SectionInset = new UIEdgeInsets(0, 0, 0, 0),
            ScrollDirection = UICollectionViewScrollDirection.Vertical,
            MinimumInteritemSpacing = 0, // minimum spacing between cells
            MinimumLineSpacing = 0,
            // minimum spacing between rows if ScrollDirection is Vertical or between columns if Horizontal
            
        };

        cvParticipants.RegisterClassForCell(typeof(ParticipantCell), ParticipantCell.participantCellId);

        cvParticipants.Source = new CVSource(dbParticipants);

        cvParticipants.Delegate = new ParticipantDelegate();

        cvParticipants.BackgroundColor = UIKit.UIColor.FromRGB(255, 215, 0);

        cvParticipants.ReloadData();

        lblTitle.Text = team + " Participants";

    }

}

The cell class:

class ParticipantCell : UICollectionViewCell
{
    UIImageView imageView { get; set; }
    UILabel lblName { get; set; }

    string EmployeeID { get; set; }        

    public static NSString participantCellId = new NSString("ParticipantCell");
    [Export("initWithFrame:")]
    public ParticipantCell(CGRect frame) : base(frame)
    {

        ContentView.Layer.BorderColor = UIColor.LightGray.CGColor;
        ContentView.Layer.BorderWidth = 2.0f;
        ContentView.BackgroundColor = UIColor.White;
        ContentView.Transform = CGAffineTransform.MakeScale(0.8f, 0.8f);



        imageView = new UIImageView(UIImage.FromBundle("placeholder.png"));
        imageView.Center = ContentView.Center;
        imageView.ContentMode = UIViewContentMode.ScaleAspectFit;
        lblName = new UILabel();

        ContentView.AddSubview(new UIView() { imageView, lblName });
    }
    public void SetImage (UIImage image, string name, string playerID)
    {
        EmployeeID = employeeID;
        imageView.Image = image;
        imageView.Frame = new CGRect(0, 0, ContentView.Bounds.Width, ContentView.Bounds.Height);
        lblName.Text = name;
        lblName.Frame = new CGRect(0, ContentView.Bounds.Height, ContentView.Bounds.Width, 26);
    }

}

The view controller and source classes:

class ParticipantViewController : UIViewController
{
    static NSString participantCellId = new NSString("ParticipantCell");
    public DataSet Participants;
    UICollectionView collectionView;
    CVSource source;
    public ParticipantViewController(UICollectionViewLayout layout, DataSet pParticipants) //: base(layout)
    {

        Participants = pParticipants;
        collectionView = new UICollectionView(UIScreen.MainScreen.Bounds, layout);
        collectionView.ContentSize = View.Frame.Size;

        source = new CVSource(pParticipants);

        collectionView.RegisterClassForCell(typeof(ParticipantCell), participantCellId);
        collectionView.Source = source;
    }

    public override void ViewDidLoad()
    {

        View = collectionView;

    }

}
class CVSource : UICollectionViewSource
{
    DataSet Participants = new DataSet();

    public override nint NumberOfSections(UICollectionView collectionView)
    {
        return 1;
    }
    public override nint GetItemsCount(UICollectionView collectionView, nint section)
    {
        return Participants.Tables[0].Rows.Count;
    }

    public CVSource(DataSet pParticipants)
    {
        Participants = pParticipants;
    }

    public override UICollectionViewCell GetCell(UICollectionView collectionView, NSIndexPath indexPath)
    {
        var participantCell = (ParticipantCell)collectionView.DequeueReusableCell(ParticipantCell.participantCellId, indexPath);
        string name = Participants.Tables[0].Rows[indexPath.Row]["Name"].ToString();
        byte[] imageBytes = (byte[])Participants.Tables[0].Rows[indexPath.Row]["Photo"];
        string employeeid= Participants.Tables[0].Rows[indexPath.Row]["employeeid"].ToString();
        UIImage Mybitmap = GetImagefromByteArray(imageBytes);
        participantCell.SetImage(Mybitmap, name, playerid); // MaxResizeImage(Mybitmap, 200f, 200f);
        return participantCell;
    }

    public static UIImage GetImagefromByteArray(byte[] imageBuffer)
    {
        NSData imageData = NSData.FromArray(imageBuffer);
        return UIImage.LoadFromData(imageData);
    }
}

Finally the delegate where I capture the selected cell:

class ParticipantDelegate : UICollectionViewDelegate
{
    public override void ItemSelected(UICollectionView collectionView, NSIndexPath indexPath)
    {
        var cell = collectionView.CellForItem(indexPath);
    }
} 

The cell does not contain any of the properties defined in participantCell and I need the information. Everything else works as expected.

Answer 1

The right way should be passing the Participants to your delegate class as what you did in the CVSource :

class ParticipantDelegate : UICollectionViewDelegate
{
    DataSet Participants = new DataSet();

    public ParticipantDelegate(DataSet pParticipants)
    {

        Participants = pParticipants;

    }

    public override void ItemSelected(UICollectionView collectionView, NSIndexPath indexPath)
    {
        var cell = collectionView.CellForItem(indexPath);
        
        //get the data
        var cellData = Participants.Tables[0].Rows[indexPath.Row];

        //For example
        string name = Participants.Tables[0].Rows[indexPath.Row]["Name"].ToString();
    }
}

And set delegate:

cvParticipants.Delegate = new ParticipantDelegate(dbParticipants);