UIView+NSLayoutConstraint.swift

import UIKit

extension UIView {
    @discardableResult func constraint(attribute attr1: NSLayoutAttribute, relatedBy: NSLayoutRelation = .equal, toItem: Any? = nil, attribute attr2: NSLayoutAttribute? = nil, multiplier: CGFloat = 1, constant: CGFloat = 0) -> NSLayoutConstraint {
        
        self.translatesAutoresizingMaskIntoConstraints = false
        
        let attr = attr2 ?? attr1
        
        return NSLayoutConstraint(item: self, attribute: attr1, relatedBy: relatedBy, toItem: toItem, attribute: attr, multiplier: multiplier, constant: constant)
    }
    
    @discardableResult func edge(insets: UIEdgeInsets, toItem: Any) -> [NSLayoutConstraint] {
        return [
            constraint(attribute: .top, toItem: toItem, constant: insets.top),
            constraint(attribute: .left, toItem: toItem, constant: insets.left),
            constraint(attribute: .right, toItem: toItem, constant: -insets.right),
            constraint(attribute: .bottom, toItem: toItem, constant: -insets.bottom)
        ]
    }
    
    @discardableResult func edge(offset: CGFloat, toItem: Any) -> [NSLayoutConstraint] {
        return edge(insets: UIEdgeInsets(top: offset, left: offset, bottom: offset, right: offset), toItem: toItem)
    }
}


// Example
let view = UIView()
let a = UIView()

view.addSubview(a)


([
    a.constraint(attribute: .width, constant: 200),
    a.constraint(attribute: .height, constant: 40),
    a.constraint(attribute: .centerX, toItem: view),
    a.constraint(attribute: .centerY, toItem: view)
] + a.edge(offset: 16, toItem: view)).forEach { (c) in
        c.isActive = true
}