AutoLayout框架Masonry
https://github.com/SnapKit/Masonry
http://archerzz.ninja/ios/masonry-code.html
http://www.cocoachina.com/ios/20141219/10702.html
http://www.starming.com/index.php?v=index&view=81&utm_source=tuicool&utm_medium=referral
http://snapkit.io/docs/