c# – 多次调用iOS TableView按钮

我有一个带有自定义UITableViewCell的TableView.在每个单元格中,我有多个按钮,当向下滚动向上按下任何按钮时,它会自动调用多次我向下和向上滚动.

我已阅读并研究解决方案,但我还没有找到解决方案.

我知道问题是单元格正在被重用,这就是为什么按钮被多次调用但我找不到防止它的方法.

我通过代码添加了控制台写行语句,而MoveToWindow中的else部分从不调用.这可能是原因吗？

解决方案的研究材料：

my code is calling twice the btndelete method in uitableview

UIButton click event getting called multiple times inside custom UITableViewCell

我的代码：

namespace Class.iOS
{
    public partial class CustomCell : UITableViewCell
    {
        public static readonly NSString Key = new NSString ("CustomCell");
        public static readonly UINib Nib;
        public int Row { get; set; }
        public event EventHandler LikeButtonPressed;

        private void OnLikeButtonPressed()
        {
            if (LikeButtonPressed != null)
            {
                LikeButtonPressed(this, EventArgs.Empty);
            }
        }

        public override void MovedToWindow()
        {
            if (Window != null)
            {
                btnAdd.TouchUpInside += HandleLikeButtonPressed;
            }
            else
            {
                btnAdd.TouchUpInside -= HandleLikeButtonPressed;
            }
        }

        private void HandleLikeButtonPressed(object sender, EventArgs e)
        {
            OnLikeButtonPressed();
        }

        static CustomCell ()
        {
            Nib = UINib.FromName ("CustomCell", NSBundle.MainBundle);
        }

        public CustomCell ()
        {           
        }

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

        public void UpdateCell (string Name, int number)
        {
            // some code
        }

        public class TableSource : UITableViewSource
        {           
            public override nint RowsInSection (UITableView tableview, nint section)
            {
                return 8;
            }

            private void HandleLikeButtonPressed(object sender, EventArgs e)
            {
                var cell = (CustomCell)sender;
                var row = cell.Row;

                switch (row) 
                {
                case 0:
                    cell.label.Text = ""
                    break;
                case 1:
                    cell.label.Text = ""
                    break;
                }
            }
            public override UITableViewCell GetCell (UITableView tableView, NSIndexPath indexPath)
            {
                var cell = tableView.DequeueReusableCell (CustomCell.Key) as CustomCell;
                cell.Row = indexPath.Row;

                if (cell == null) 
                {
                    cell = new CustomCell ();
                    var views = NSBundle.MainBundle.LoadNib("CustomCell", cell, null);
                    cell.LikeButtonPressed += HandleLikeButtonPressed;
                    cell = Runtime.GetNSObject( views.ValueAt(0) ) as CustomCell;

                }

                cell.UpdateCell 
                (
                    // some code
                );

                return cell;
            }
        }
    }
}

解决方法:

单元格在iOS中重复使用,因此您需要确保在重用单元格时正确解开处理程序并重置状态.你可以这样做：

public partial class CustomCell : UITableViewCell {

EventHandler _likeButtonHandler;

public static readonly NSString Key = new NSString (typeof(CustomCell).Name);
public static readonly UINib Nib = UINib.FromName (typeof(CustomCell).Name, NSBundle.MainBundle);

public CustomCell ()
{

}

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

public override void PrepareForReuse ()
{
    LikeButton.TouchUpInside -= _likeButtonHandler;
    _likeButtonHandler = null;

    base.PrepareForReuse ();
}

public void SetupCell (int row, string Name, EventHandler likeBtnHandler)
{
    _likeButtonHandler = likeBtnHandler;

    LikeButton.TouchUpInside += _likeButtonHandler;
    LikeButton.Tag = row;

    NameLabel.Text = Name;
    RowLabel.Text = row.ToString ();
}

请注意,我在PrepareForReuse覆盖中取消了事件处理程序.这是清理和重置单元以供重用的正确位置.你不应该使用MovedToWindow().

然后你的GetCell方法将如下所示：

public override UITableViewCell GetCell (UITableView tableView, NSIndexPath indexPath)
{
    var cell = tableView.DequeueReusableCell (CustomCell.Key) as CustomCell ?? new CustomCell ();

    cell.SetupCell (indexPath.Row, _fruits [indexPath.Row], _likeButtonHandler);

    return cell;
}

_likeButtonHandler是一个简单的EventHandler.