Swift: Create Facebook (Part 2) – UICollectionView, NSLayoutConstraint
my review point is 8/10
https://youtu.be/ZwBYQpLQAvw?t=8m15s button style ( setTitle, setTitleColor , setImage , titleEdgeInsets)
https://youtu.be/ZwBYQpLQAvw?t=14m35s equally spaced out elements
https://youtu.be/ZwBYQpLQAvw?t=18m37s refresh collection view when user change orientation ( viewWillTransitionToSize , invalidateLayout)
(Source: https://www.youtube.com/)