title: iOS: UICollectionViewCell auto adjust size according to screen size
body: <p>I am trying to create 10 cells in the collection view(same size as the screen). When I run my app in iphone5s simulator, the view contains exactly 5 cells. But when I switch to iphone6p simulator, the view contains more than 5 cells. How should I adjust the cell size so that the number of cells in screen are consistent across different screen sizes?</p>