One view controller with multiple views vs multiple view controllers in a bigger view controller

Let's say A, B, C each is a relatively independent component of the view, with distinctive features, like, 3 different calculators, should I use one view controller with multiple views, or multiple view controllers in a bigger view controller?

There's this project on github, the MengTo seems to choose for the multiple view controller way: http://ift.tt/1tMhamB