UIViewLayoutConstraintExtensions.swift

extension NSLayoutConstraint {
    
    public convenience init(item view1: Any,
                            toItem view2: Any? = nil,
                            relatedBy relation: NSLayoutRelation = .equal,
                            attribute sharedAttribute: NSLayoutAttribute,
                            multiplier: CGFloat = 1,
                            constant c: CGFloat) {
        self.init(item: view1,
                  attribute: sharedAttribute,
                  relatedBy: relation,
                  toItem: view2,
                  attribute: sharedAttribute,
                  multiplier: multiplier,
                  constant: c)
    }
    
}

extension UIView {
    
    @discardableResult func activateConstraint(to item: UIView? = nil,
                                               attribute: NSLayoutAttribute,
                                               constant: CGFloat) -> NSLayoutConstraint {
        let constraint = NSLayoutConstraint(item: self, toItem: item, attribute: attribute, constant: constant)
        constraint.isActive = true
        return constraint
    }
    
    @discardableResult func activateConstraints(to item: UIView? = nil,
                                                attributes: [NSLayoutAttribute],
                                                constant: CGFloat) -> [NSLayoutConstraint] {
        var constraints: [NSLayoutConstraint] = []
        for attribute in attributes {
            constraints.append(activateConstraint(to: item, attribute: attribute, constant: constant))
        }
        return constraints
    }
    
    @discardableResult func activateConstraints(to item: UIView,
                                                using edgeInsets: UIEdgeInsets) -> [NSLayoutConstraint]  {
        var constraints: [NSLayoutConstraint] = []
        constraints.append(activateConstraint(to: item, attribute: .leading, constant: edgeInsets.left))
        constraints.append(activateConstraint(to: item, attribute: .trailing, constant: edgeInsets.right))
        constraints.append(activateConstraint(to: item, attribute: .top, constant: edgeInsets.top))
        constraints.append(activateConstraint(to: item, attribute: .bottom, constant: edgeInsets.bottom))
        return constraints
    }
    
    @discardableResult func activateConstraintsToSuperview(using edgeInsets: UIEdgeInsets = .zero) -> [NSLayoutConstraint] {
        var constraints: [NSLayoutConstraint] = []
        if let superview = superview {
            constraints = activateConstraints(to: superview, using: edgeInsets)
        }
        return constraints
    }
    
}