Create individual constraints for different iPhone sizes (not interested in the iPad)

Depends what you want to achieve.

Those constraints for inbstance will yield same result on all :

- center vertically or horizontally in superview

- leading or trailing to superview

- top or bottom to superview

In fact, you ought to set constraints relative to safe area.

For exeample, on the iPhone SE on portrait I want the constraint to the top to be 20 and on the iPhone X I want that same constrait on portrait to be 40.

How do I achieve that?

>I am only developing for iPhone in portrait.

Actually, you're not. Review expects your app, even if iPhone-only, to not look bad when run in 1x/2x mode on iPad, and unless you can show a hard requirement for not providing landscape support, you can expect push back during review.

>How can I set different constrait sizes on the different sizes?

See:

- https://developer.apple.com/design/adaptivity/Auto Layout

- https://developer.apple.com/design/tips/

Why do you want 20 and then 40 ?

If it is because of the notch, the safe area is just done for this.

This was just an example. In some displays I want the elements to be "more together". In larger displays I would like to see the elements further from each other.

Does it work if I change the relation to greater than or equal?

If you want to adapt to screen size, you can adjust the constraints in code.

- create an IBOutlet for the constraint :

@IBOutlet var topConstraint: NSLayoutConstraint!

- change its value where you need (may be in viewDidLoad

if screenSize.height > someValue {
     topConstraint.constant = 40
} else {
     topConstraint.constant = 20
}

If I do that, can I set the constraints on the storyboard?

Yes, you first define constraints in the storyboard, for instance at 20.

You create the IBOutlet for the constraint: control-drag from the constraint (in the pane that lists all objects) to the code

Then you modify them in code, as proposed.