iOS texting bubble physics at work

Question

On an iPhone, in the standard messaging app, the text bubble will keep going up even after it has seemingly met the edge-of-the-screen limit, if you keep pushing it with two fingers.

What is allowing that to happen?

How would I replicate that so my code isn't so "fixed" and just stops exactly at the variable where it's supposed to?

Also, is there a name for the "bouncy" text physics that we see in android and iOS?

Answer 1

Don't make a boundary - make a constraint.

Is it the case that you can't push the bubble 'outside of the screen', or is it more that you can't drag it further than the initial drag point?

Answer 2

UIKit Dynamics is the high level name. http://www.doubleencore.com/2013/09/ios-7-uikit-dynamics/