scrolling beyond bottom in iOS

I have a scrollable text field where the text changes programmatically. when I scroll up to see the end of the text, I can keep scrolling so that all of the text scrolls out of site (this is bad). I should only be able to scroll up until I reach the end of the text.

Even worse, something in the scrolling goes into an infinite loop, and the app starts use up memory until I have to kill it.

I assume that it is something that is set wrong in Main.storyboard, but I am not sure.

Andy ideas?

scrolling beyond bottom in iOS
 
 
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