Layout Anchor Helpers

UIView+Helpers.swift

import Foundation
import UIKit

extension UIView {
    func addSubviews(_ subviews: [UIView]) {
        for view in subviews {
            addSubview(view)
        }
    }
}

extension UIView {
    @discardableResult
    func anchorToCenter(of view: UIView, offset: CGPoint = .zero) -> [NSLayoutConstraint] {
        return view.apply(constraints: [
            centerXAnchor.constraint(equalTo: view.centerXAnchor, constant: offset.x),
            centerYAnchor.constraint(equalTo: view.centerYAnchor, constant: offset.y),
        ])
    }

    @discardableResult
    func anchorToCenterOfSuperview(offset: CGPoint = .zero) -> [NSLayoutConstraint] {
        return anchorToCenter(of: superview!, offset: offset)
    }

    @discardableResult
    func anchorToEdges(of view: UIView, insets: UIEdgeInsets = .zero) -> [NSLayoutConstraint] {
        return view.apply(constraints: [
            topAnchor.constraint(equalTo: view.topAnchor, constant: insets.top),
            bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -insets.bottom),
            leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: insets.left),
            trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -insets.right),
        ])
    }

    @discardableResult
    func anchorToEdgesOfSuperview(insets: UIEdgeInsets = .zero) -> [NSLayoutConstraint] {
        return anchorToEdges(of: superview!, insets: insets)
    }

    @discardableResult
    func apply(constraints: [NSLayoutConstraint]) -> [NSLayoutConstraint] {
        constraints.forEach({ self.apply(constraint: $0) })

        return constraints
    }

    @discardableResult
    func apply(constraint: NSLayoutConstraint) -> NSLayoutConstraint {
        (constraint.firstItem as? UIView)?.translatesAutoresizingMaskIntoConstraints = false
        constraint.isActive = true

        return constraint
    }
}