CODEWITHSUNDEEP
swiftautolayoutconstraints
PaFi
PaFi

Reputation: 920

Updating Constraints programmatically?

I have a subclass of UIView, I want to manipulate a constraint but it does not work.

When pressing a button exchangesViewActivated changes and the functions get called.

var exchangesViewActivated = false {
    didSet {
        if exchangesViewActivated == true {
            setExchangesView()
        } else {
            setUpLayout()
        }
    }
}

Die subview and translatesAutoresizingMaskIntoConstraints are set.

func setUpLayout() {

    bottomContainer.heightAnchor.constraint(equalToConstant: 500).isActive = true


    bottomContainer.leadingAnchor.constraint(equalTo: scrollViewContrainer.leadingAnchor).isActive = true
    bottomContainer.trailingAnchor.constraint(equalTo: scrollViewContrainer.trailingAnchor).isActive = true
    bottomContainer.topAnchor.constraint(equalTo: configBar.bottomAnchor).isActive = true
    bottomContainer.bottomAnchor.constraint(equalTo: scrollViewContrainer.bottomAnchor).isActive = true

}

Now I want to manipulate the constraint by calling this function:

 func setExchangesView() {

bottomContainer.bottomAnchor.constraint(equalTo: scrollViewContrainer.bottomAnchor).isActive = false

        bottomContainer.heightAnchor.constraint(equalToConstant: 500).isActive = false
        bottomContainer.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: 0).isActive = true
}

But this constraint stays activated:

bottomContainer.heightAnchor.constraint(equalToConstant: 500).isActive

Am I missing something? Is it not enough to set a constraint to false to deactivate it? Do I have to call something else?

Upvotes: 0

Views: 987

Answers (2)

Bilal
Bilal

Reputation: 19156

setUpLayout() is adding new constraints every time you call setUpLayout() method. You must save constraint reference and update it next time.

For example.

// class variable 
var bottomConstraint:NSLayoutConstraint? = nil

bottomConstraint = bottomContainer.heightAnchor.constraint(equalToConstant: 500)
bottomConstraint.isActive = true

And later update constraint

bottomConstraint.constant = 100
bottomConstraint.isActive = true

Upvotes: 2

Shehata Gamal
Shehata Gamal

Reputation: 100541

This doesn't deactivate old constraints as it deactivates the newly created ones so do

var heightCon:NSLayoutConstraint!
var botCon:NSLayoutConstraint!

//

heightCon = bottomContainer.heightAnchor.constraint(equalToConstant: 500)
heightCon.isActive = true

botCon = bottomContainer.bottomAnchor.constraint(equalTo: scrollViewContrainer.bottomAnchor)
botCon.isActive = true

Then you can easily reference the constraints and deactivates them and add the new constraints

Upvotes: 1

Related Questions