It is challenging to create a UI that looks good and works well on multiple devices with different screen sizes and different pixel densities. IOS handles this using the concept of constraints. Instead of giving fixed sizes and positions, you specify relationships such as “align these two views vertically” or “stretch this view to fit all the available space”. This course first shows you how to use constraints to layout the views on a single screen. It then broadens the discussion to show you how to use segues to link together multiple pages in your app.