I have a horizontal paging UIScrollview, following is my VFL constraints for leading/trailing H:|-0-[ScrollView]-0-| (aligned to superview).
UIScrollview
H:|-0-[ScrollView]-0-|
If you set UIScrollview.contentInsetAdjustmentBehavior = .never, you'll be responsible for applying the insets. If you let to the default value, any time the view needs to be redrawn, the framework will override your settings