The layout that
UICollectionView provides out of the box is a grid layout. All items are evenly spaced and sized. To visualize this, open up the storyboard file, select the cell, give it a background color, and run the app. This will make the grid layout really obvious, and it also shows how the constraints nicely center the UI elements inside of the cell.
The ease of use and the performance of the
UICollectionView make this a great way for your app to use a grid layout. However, the current implementation of the grid is not perfect yet. The grid looks alright on an iPhone 6s; but on an iPhone SE, the layout looks like it's falling apart and it doesn't look much better when viewed on ...