Dynamic UITableViewCell based on UILabel - ios

Question

Working with Xamarin.ios and I need my UITableViewCell to adjust its height based on the size (number of lines of text) of a UILabel. I have a custom UITableViewCell where the UILabel is created and the text is set based on user input. The only way I really know how to adjust the height of the cell is in the UITableViewSource class using the public override nint RowsInSection(UITableView tableview, nint section) method.
public class ChatTableSource : UITableViewSource
{
public List<MessageDetails> messages;
public ChatTableSource()
{
}
public override UITableViewCell GetCell(UITableView tableView, NSIndexPath indexPath)
{
CustomMessageCell cell = tableView.DequeueReusableCell(cellIdentifier) as CustomMessageCell;
// if there are no cells to reuse, create a new one
if (cell == null)
cell = new CustomMessageCell(cellIdentifier);
tableView.Layer.BackgroundColor = UIColor.White.CGColor;
cell.UpdateCell(messages[indexPath.Row].body);
return cell;
}
public override nint RowsInSection(UITableView tableview, nint section)
{
return messages.ToArray().Length;
}
//public override nfloat GetHeightForRow(UITableView tableView, NSIndexPath indexPath)
//{
// return dynamic size
//}
}
public class CustomMessageCell : UITableViewCell
{
UILabel body;
public CustomMessageCell(NSString cellId) : base(UITableViewCellStyle.Default, cellId)
{
body = new UILabel();
ContentView.Add(body);
}
public void UpdateCell(string body)
{
this.body.Text = body;
}
public override void LayoutSubviews()
{
base.LayoutSubviews();
body.Frame = new CGRect(distanceFromScreenEdge, ContentView.Bounds.Top, longTextSize, ContentView.Bounds.Height);
body.Lines = 0;
}
}

Answer 1

I don't work with Xamarin - so I can't test this - but this should be what you want to do...
Use constraints and let auto-layout handle the sizing for you.
public class CustomMessageCell : UITableViewCell
{
UILabel body;
public CustomMessageCell(NSString cellId) : base(UITableViewCellStyle.Default, cellId)
{
body = new UILabel();
ContentView.Add(body);
var margins = View.LayoutMarginsGuide;
// Pin the leading edge of body to the margin
body.LeadingAnchor.ConstraintEqualTo (margins.LeadingAnchor).Active = true;
// Pin the trailing edge of body to the margin
body.TrailingAnchor.ConstraintEqualTo (margins.TrailingAnchor).Active = true;
// Pin the top edge of body to the margin
body.TopAnchor.ConstraintEqualTo (margins.TopAnchor).Active = true;
// Pin the bottom edge of body to the margin
body.BottomAnchor.ConstraintEqualTo (margins.BottomAnchor).Active = true;
// set body number of lines to Zero so it will automatically set its own height
body.Lines = 0
}
public void UpdateCell(string body)
{
this.body.Text = body;
}
}
You don't need LayoutSubviews() at all.