deactivate nslayoutconstraint declared in viewdidload with function

Question

My code below declares layout constraints in viewdidload. When the function Selena is called I would like the the constraints to be change to what is in the function selena. When I call the function the object I does not change. It has no effect. I know somehow I have to deactivate the original constraints.

   override func viewDidLoad() {

    NSLayoutConstraint.activate ([
        i.trailingAnchor.constraint(equalTo: view.centerXAnchor, constant :150),
        i.topAnchor.constraint(equalTo: view.centerYAnchor, constant : -200),

        i.widthAnchor.constraint(equalToConstant: 300),
        i.heightAnchor.constraint(equalToConstant: 450),

    ])

}


@objc func selena(){
    NSLayoutConstraint.activate ([
        i.trailingAnchor.constraint(equalTo: view.centerXAnchor, constant :50),
        i.topAnchor.constraint(equalTo: view.centerYAnchor, constant : -50),

        i.widthAnchor.constraint(equalToConstant: 20),
        i.heightAnchor.constraint(equalToConstant: 450),

    ])

}

Answer 1

You can hold a reference to them then use deactivate

  var oldCons = [NSLayoutConstraint]()

   override func viewDidLoad() {
       super.viewDidLoad()
     oldCons = [
        i.trailingAnchor.constraint(equalTo: view.centerXAnchor, constant :150),
        i.topAnchor.constraint(equalTo: view.centerYAnchor, constant : -200), 
        i.widthAnchor.constraint(equalToConstant: 300),
        i.heightAnchor.constraint(equalToConstant: 450)
     ]
    NSLayoutConstraint.activate(oldCons)

}


@objc func selena(){

    NSLayoutConstraint.deactivate(oldCons)
    NSLayoutConstraint.activate ([
        i.trailingAnchor.constraint(equalTo: view.centerXAnchor, constant :50),
        i.topAnchor.constraint(equalTo: view.centerYAnchor, constant : -50), 
        i.widthAnchor.constraint(equalToConstant: 20),
        i.heightAnchor.constraint(equalToConstant: 450) 
    ])


}

---

height connstraint didn't change you can get it out of the array inside viewDidLoad

 i.heightAnchor.constraint(equalToConstant: 450).isActive = true

and remove it from selena function