Removing constraints that were added programatically

Question

I read many topics about how to remove constraints that were added through the storyboard, drag outlet and then remove etc. but how I can remove constraints that were added programmatically? For example

firstView.topAnchor.constraints(equalTo: secondView.bottomAnchor, constant: 15).isActive = true

how can I deactivate it and then enable it again if needed. Maybe it should be something like?

firstView.removeConstraint(firstView.topAnchor.constraints(equalTo: secondView.bottomAnchor))

Answer 1

You should assign your constraint to a property in your ViewController. And then set .isActive to false instead of true.

Your code should look like this:

let myConstraint = firstView.topAnchor.constraint(equalTo: secondView.bottomAnchor, constant: 15)

Now, to activate it:

myConstraint.isActive = true

And to disable it:

myConstraint.isActive = false

Answer 2

You need to keep a reference to your constraint.

let constraintName: NSLayoutConstraint = firstView.topAnchor.constraint(equalTo: secondView.bottomAnchor, constant: 15)
constraintName.isActive = true

Disable it when you don't need it.

constraintName.isActive = false

Enable it when you want it back.

constraintName.isActive = true