Get reference to NSLayoutConstraint using Identifier set in storyboard

Question

I was setting the constraints of a button using a storyboard. I saw an option, \"Identifier\" in the constraint\'s properties.

Answer 1

For resizing a set of buttons within a common view container this works. Each subview/button must use a common identifier (e.g. "height").

@IBAction func btnPressed(_ sender: UIButton) {
    for button in self.btnView.subviews{
        for constraint in button.constraints{
            if constraint.identifier == "height"{
                constraint.constant = constraint.constant == 0 ? 30:0
            }
        }
    }
    UIView.animate(withDuration: 0.3) { () -> Void in
        self.view.layoutIfNeeded()
    }
}