Question

我在表格视图中具有单元格中的图像

但是当数据显示在TableView中并滚动时，它并不平滑。但是我认为所有图像都已下载。

这是TableView源代码

public class ExperienceSource : UITableViewSource
{

    //UINavigationController instance, to pass it to constructor
    private UINavigationController primNav { get; set; }
    private UITableView tableView { get; set; }
    List<Experience> TableItems;
    ExperienceTableViewController owner;
    public ExperienceSource(List<Experience> items,ExperienceTableViewController owner, UINavigationController nav)
    {
        TableItems = items;
        this.owner = owner;
        primNav = nav;
    }


    public override nint RowsInSection(UITableView tableview, nint section)
    {

        if (TableItems.Count == 0)
        {


            var noDataLabel = new UILabel
            {
                Text = "No Experiences at your location at this time. Try to change destination",
                TextColor = UIColor.Black,
                TextAlignment = UITextAlignment.Center,
                LineBreakMode = UILineBreakMode.WordWrap,
                Lines = 0
            };
            tableview.BackgroundView = noDataLabel;
            tableview.SeparatorStyle = UITableViewCellSeparatorStyle.None;

            return TableItems.Count;
        }
        else
        {

            tableview.SeparatorStyle = UITableViewCellSeparatorStyle.SingleLine;
            return TableItems.Count;
        }


    }

    public override async void RowSelected(UITableView tableView, NSIndexPath indexPath)
    {
        var selectedExperience = await ExperienceMethods.GetSelectedTour(TableItems[indexPath.Row].id);
        if (selectedExperience == "Saved")
        {
        ExperienceDetailViewController ExperienceDetailController = primNav.Storyboard.InstantiateViewController("ExperienceDetailViewController") as ExperienceDetailViewController;
        primNav.PushViewController(ExperienceDetailController, true);

        }
        else
        {
          UIAlertController okAlertController = UIAlertController.Create("", "Cannot select this experience", UIAlertControllerStyle.Alert);
        okAlertController.AddAction(UIAlertAction.Create("OK", UIAlertActionStyle.Default, null));
        }
        tableView.DeselectRow(indexPath, true);
    }


    public override UITableViewCell GetCell(UITableView tableView, NSIndexPath indexPath)
    {
        var cell = tableView.DequeueReusableCell("cell_id", indexPath) as ExperienceCell;
        Experience item = TableItems[indexPath.Row];
        cell.UpdateCell(item);
        return cell;
    }

我在此类中有自定义单元格的代码

 public partial class ExperienceCell : UITableViewCell
{
    public ExperienceCell (IntPtr handle) : base (handle)
    {
    }
    internal void UpdateCell(Experience experience)
    {
        UIImage picture;
        try
        {
            var image_url = "https://xplorpal.com/" + experience.cover_image.img_path + "/300x300/" + experience.cover_image.img_file;
            using (var url = new NSUrl(image_url))
            using (var data = NSData.FromUrl(url))
                picture = UIImage.LoadFromData(data);
            ExperienceImage.Image = picture;
        }
        catch { }
        finally
        {
            ExperienceTitle.Text = experience.title;
            ExperiencePrice.Text = "$" + experience.price;
        }
    }
}

我的问题在哪里？如何优化此TableView的滚动？

感谢您的帮助。

Answer 1

我不熟悉在TableViewCell中使用NSData.FromUrl方法，但是在大多数情况下，手动处理远程图像是一个坏主意。

您应该考虑使用SDWebImage之类的库，该库将为您处理下载，缓存并将图像分配给UIImage。

TableView滚动不流畅（Xamarin.iOS）

1 个答案: