iOS - Find top constraint for a view?

Question

I am trying to find the top constraint of the view in code. The top constraint is added in storyboard, and I don\'t want to use an IBOutlet.

Logging the value of the

Answer 1

Based on @Igor answer, I changed a bit itemMatch method to consider when first item or second item is not a UIView. For example when constraint a UIView top to safe area top.

extension UIView {
    func findConstraint(layoutAttribute: NSLayoutConstraint.Attribute) -> NSLayoutConstraint? {
        if let constraints = superview?.constraints {
            for constraint in constraints where itemMatch(constraint: constraint, layoutAttribute: layoutAttribute) {
                return constraint
            }
        }
        return nil
    }

    func itemMatch(constraint: NSLayoutConstraint, layoutAttribute: NSLayoutConstraint.Attribute) -> Bool {
        let firstItemMatch = constraint.firstItem as? UIView == self && constraint.firstAttribute == layoutAttribute
        let secondItemMatch = constraint.secondItem as? UIView == self && constraint.secondAttribute == layoutAttribute
        return firstItemMatch || secondItemMatch
    }
}