Designable view from xib, with optimisation

UIViewXib.swift

@IBDesignable
class UIViewXib: UIView {
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        loadViewFromNib()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        loadViewFromNib()
    }
    
    private func loadViewFromNib() {
        let bundle = Bundle(for: type(of: self))
        let nib = UINib(nibName: String(describing: type(of: self)), bundle: bundle)
        if let view = nib.instantiate(withOwner: self, options: nil).first as? UIView {
            
            let consts = view.constraints
            
            view.subviews.forEach {
                $0.removeFromSuperview()
                addSubview($0)
            }
            
            consts.forEach {
                let firstItem = $0.firstItem === view ? self : $0.firstItem
                let secondItem = $0.secondItem === view ? self : $0.secondItem
                addConstraint(.init(item: firstItem!, attribute: $0.firstAttribute, relatedBy: $0.relation, toItem: secondItem!, attribute: $0.secondAttribute, multiplier: $0.multiplier, constant: $0.constant))
            }
        }
        
        // low priority default height constraint
        let heightConst = heightAnchor.constraint(equalToConstant: 100)
        heightConst.priority = .init(1)
        heightConst.isActive = true
    }
}