Remove constraints iOS - ios

Question

I try to remove constraints. I want to different constraints on portrait and landscape. If I change the orientation to Portrait I call the function setupConstrainsInPortrait and conversely. I have two functions.
This function setup Portrait mode.
func setupConstrainsInPortrait() {
view.addSubview(myView)
myView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
myView.topAnchor.constraint(equalTo: view.topAnchor, constant: 50).isActive = true
myView.heightAnchor.constraint(equalToConstant: 300).isActive = true
myView.widthAnchor.constraint(equalToConstant: view.frame.size.width).isActive = true
view.addSubview(switchKmM)
switchKmM.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
switchKmM.topAnchor.constraint(equalTo: myView.bottomAnchor, constant: 10).isActive = true
switchKmM.heightAnchor.constraint(equalToConstant: 50).isActive = true
switchKmM.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true
view.addSubview(speedLbl)
speedLbl.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
speedLbl.topAnchor.constraint(equalTo: view.bottomAnchor, constant: -50).isActive = true
speedLbl.heightAnchor.constraint(equalToConstant: 50).isActive = true
speedLbl.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true
}
This function setup landscape mode.
func setupConstrainsInLandScape() {
view.addSubview(myView)
myView.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 10).isActive = true
myView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
myView.heightAnchor.constraint(equalToConstant: 300).isActive = true
myView.widthAnchor.constraint(equalToConstant: 150).isActive = true
view.addSubview(switchKmM)
switchKmM.leftAnchor.constraint(equalTo: myView.rightAnchor, constant: 30).isActive = true
switchKmM.topAnchor.constraint(equalTo: view.topAnchor, constant: 30).isActive = true
switchKmM.heightAnchor.constraint(equalToConstant: 50).isActive = true
switchKmM.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true
}
I use these functions in viewWillTransition
override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
if UIDevice.current.orientation.isLandscape {
print("landscape!")
view.backgroundColor = .green
setupConstrainsInLandScape()
self.viewWillLayoutSubviews()
}
else {
print("portrét")
view.backgroundColor = .white
setupConstrainsInPortrait()
self.viewWillLayoutSubviews()
}
super.viewWillTransition(to: size, with: coordinator)
}
The problem is, that constraints(from portrait function) in landscape mode aren't deleted
I hope that someone can help me... Thank you

Answer 1

You're not doing enough work. You need to retain references to all the constraints you activate, so that you can deactivate them later. For example, you are saying:
myView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
myView.topAnchor.constraint(equalTo: view.topAnchor, constant: 50).isActive = true
myView.heightAnchor.constraint(equalToConstant: 300).isActive = true
myView.widthAnchor.constraint(equalToConstant: view.frame.size.width).isActive = true
Instead, you need to say something like
self.myConstraints1 = [
myView.centerXAnchor.constraint(equalTo: view.centerXAnchor),
myView.topAnchor.constraint(equalTo: view.topAnchor, constant: 50),
myView.heightAnchor.constraint(equalToConstant: 300),
myView.widthAnchor.constraint(equalToConstant: view.frame.size.width),
]
Now activate all those constraints. Proceed the same way throughout.
Thus, when the time comes to deactivate constraints because the orientation is changing, you have references to them and can do so.

Answer 2

You can remove your constraints using:
myView.constraints.removeAll()
Before setting the new ones.