An easy way to implement your own UITextView placeholder field without subclassing.

CommentsTextDelegate.cs

		public class CommentsTextDelegate : UITextViewDelegate
		{
			public override void EditingStarted (UITextView textView)
			{
				if (textView.Text == "Comments") {
					textView.Text = "";
					textView.TextColor = UIColor.Black;
					textView.Font = FontConstants.SourceSansProRegular (13);
				}

				textView.BecomeFirstResponder ();
			}

			public override void EditingEnded (UITextView textView)
			{
				if (textView.Text == "") {
					textView.Text = "Comments";
					textView.TextColor = UIColor.LightGray;
					textView.Font = FontConstants.SourceSansProBold (13);
				}

				textView.ResignFirstResponder ();
			}
		}
	}