UIView+ConstraintsSugar.swift

import UIKit

@objc
extension UIView {
    func constrain(_ constraints: [NSLayoutConstraint]) {
        translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate(constraints)
    }

    @discardableResult
    func constrainEdges(to view: UIView, insets: UIEdgeInsets) -> [NSLayoutConstraint] {
        let constraints = constraintsForEdges(to: view, insets: insets)
        constrain(constraints)
        return constraints
    }

    @discardableResult
    func constrainEdges(to view: UIView, inset: CGFloat = 0) -> [NSLayoutConstraint] {
        let constraints = constraintsForEdges(to: view, inset: inset)
        constrain(constraints)
        return constraints
    }

    @discardableResult
    func constrainCenter(to view: UIView) -> [NSLayoutConstraint] {
        let constraints = constraintsForCenter(to: view)
        constrain(constraints)
        return constraints
    }

    @discardableResult
    func constrainSize(to size: CGSize, priority: UILayoutPriority = UILayoutPriority.required) -> [NSLayoutConstraint] {
        let constraints = constraintsFor(size: size)
        constraints.forEach { $0.priority = priority }
        constrain(constraints)
        return constraints
    }

    @discardableResult
    func constrainSize(width: CGFloat, height: CGFloat, priority: UILayoutPriority = UILayoutPriority.required) -> [NSLayoutConstraint] {
        let constraints = constraintsFor(width: width, height: height)
        constraints.forEach { $0.priority = priority }
        constrain(constraints)
        return constraints
    }

    func constraintsForEdges(to view: UIView, inset: CGFloat = 0) -> [NSLayoutConstraint] {
        let insets = UIEdgeInsets(top: inset, left: inset, bottom: inset, right: inset)
        return constraintsForEdges(to: view, insets: insets)
    }

    func constraintsForEdges(to view: UIView, insets: UIEdgeInsets) -> [NSLayoutConstraint] {
        return [
            leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: insets.left),
            trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -insets.right),
            topAnchor.constraint(equalTo: view.topAnchor, constant: insets.top),
            bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -insets.bottom),
        ]
    }

    func constraintsForCenter(to view: UIView) -> [NSLayoutConstraint] {
        return [
            centerXAnchor.constraint(equalTo: view.centerXAnchor),
            centerYAnchor.constraint(equalTo: view.centerYAnchor),
        ]
    }

    func constraintsFor(width: CGFloat, height: CGFloat) -> [NSLayoutConstraint] {
        return [
            widthAnchor.constraint(equalToConstant: width),
            heightAnchor.constraint(equalToConstant: height),
        ]
    }

    func constraintsFor(size: CGSize) -> [NSLayoutConstraint] {
        return [
            widthAnchor.constraint(equalToConstant: size.width),
            heightAnchor.constraint(equalToConstant: size.height),
        ]
    }
}