iOS 13 Disclosure button (UITableViewCellAccessory.DetailDisclosureButton) not firing event Xamarin - xamarin

Question

We have discovered in our Xamarin app in iOS 13 that the disclosure button action is not firing. Our basic code looks like this in a GridCell Class. It had been firing in iOS 12. Is there another event delegate in iOS 13?
[EventDelegate("accessorySelected")]
public event EventHandler AccessorySelected
{
add
{
accessorySelected += value;
SetAccessory();
}
remove
{
accessorySelected -= value;
SetAccessory();
}
}
private event EventHandler accessorySelected;
private void SelectAccessory(object sender, EventArgs args)
{
var handler = accessorySelected;
if (handler != null)
{
handler(Pair ?? this, EventArgs.Empty);
}
else
{
... Action Code ....
}
}

Answer 1

Delving into this code, it was not what was expected. It actually dates from 2011 and the code to load the disclosure event was unconventional, or as another one of our developers called it during this review, "Anti-pattern".
public class GridCell : UITableViewCell, INotifyPropertyChanged
{
...
public override void LayoutSubviews()
{
base.LayoutSubviews();
// I do not like going off of the frame width. The ContentView frame width would be preferred,
// but we would first need to ensure that its value is correctly adjusted in case of a disclosure.
// This should happen automatically, but it doesn't always happen in time for PerformLayout.
// There also seem to be cases where the adjusted value is not entirely accurate.
float width = (float)Frame.Width;
if (UIDevice.CurrentDevice.CheckSystemVersion(7, 0))
{
width -= (Accessory == UITableViewCellAccessory.DetailDisclosureButton ? 67 :
Accessory == UITableViewCellAccessory.DisclosureIndicator ? 33 : 0);
}
else
{
width -= (Accessory == UITableViewCellAccessory.DetailDisclosureButton ? 33 :
Accessory == UITableViewCellAccessory.DisclosureIndicator ? 20 : 0);
}
width = Math.Max(width, 0);
var size = this.PerformLayout(new iFactr.UI.Size(width, Math.Max(MinHeight - 1, 0)), new iFactr.UI.Size(width, Math.Max(MaxHeight - 1, 0)));
ContentView.Frame = new CGRect(0, 0, (float)size.Width, (float)size.Height);
Frame = new CGRect(Frame.Location, new CGSize(Frame.Width, ContentView.Frame.Height));
// Checking subview for Disclosure - iOS 13 changed 2019 subview
var disclosure = this.GetSubview<UIControl>(c => c.Description.StartsWith("<UITableViewCellDetailDisclosureView") || c.Description.StartsWith("<UIButton"));
var dlog = this.GetSubview<UIControl>();
if (disclosure != null)
{
//Setting Disclosure button (i) event
disclosure.TouchUpInside -= SelectAccessory;
disclosure.TouchUpInside += SelectAccessory;
}
}
...
}
And the change was to this line to look for UIButton now along with UITableViewCellDetailDisclosureView
var disclosure = this.GetSubview<UIControl>(
c => c.Description.StartsWith("<UITableViewCellDetailDisclosureView")
|| c.Description.StartsWith("<UIButton")); // <-- the "fix"