UIViewToolKit.swift

import UIKit

@objc extension UIView {

    @nonobjc public func addConstraintsWithFormat(_ format: String, views: UIView...) {
        var viewsDictionary = [String: UIView]()
        for (index, view) in views.enumerated() {
            let key = "v\(index)"
            viewsDictionary[key] = view
            view.translatesAutoresizingMaskIntoConstraints = false
        }

        addConstraints(NSLayoutConstraint.constraints(withVisualFormat: format, options: NSLayoutFormatOptions(), metrics: nil, views: viewsDictionary))
    }

    @objc public func fillSuperview() {
        translatesAutoresizingMaskIntoConstraints = false
        if let superview = superview {
            leftAnchor.constraint(equalTo: superview.leftAnchor).isActive = true
            rightAnchor.constraint(equalTo: superview.rightAnchor).isActive = true
            topAnchor.constraint(equalTo: superview.topAnchor).isActive = true
            bottomAnchor.constraint(equalTo: superview.bottomAnchor).isActive = true
        }
    }

    @objc public func anchor(to top: NSLayoutYAxisAnchor? = nil, left: NSLayoutXAxisAnchor? = nil, bottom: NSLayoutYAxisAnchor? = nil, right: NSLayoutXAxisAnchor? = nil, topConstant: CGFloat = 0, leftConstant: CGFloat = 0, bottomConstant: CGFloat = 0, rightConstant: CGFloat = 0, widthConstant: CGFloat = 0, heightConstant: CGFloat = 0) {
        translatesAutoresizingMaskIntoConstraints = false

        _ = anchorWithReturnAnchors(top, left: left, bottom: bottom, right: right, topConstant: topConstant, leftConstant: leftConstant, bottomConstant: bottomConstant, rightConstant: rightConstant, widthConstant: widthConstant, heightConstant: heightConstant)
    }

    @objc public func anchorWithReturnAnchors(_ top: NSLayoutYAxisAnchor? = nil, left: NSLayoutXAxisAnchor? = nil, bottom: NSLayoutYAxisAnchor? = nil, right: NSLayoutXAxisAnchor? = nil, topConstant: CGFloat = 0, leftConstant: CGFloat = 0, bottomConstant: CGFloat = 0, rightConstant: CGFloat = 0, widthConstant: CGFloat = 0, heightConstant: CGFloat = 0) -> [NSLayoutConstraint] {
        translatesAutoresizingMaskIntoConstraints = false

        var anchors = [NSLayoutConstraint]()

        if let top = top {
            anchors.append(topAnchor.constraint(equalTo: top, constant: topConstant))
        }

        if let left = left {
            anchors.append(leftAnchor.constraint(equalTo: left, constant: leftConstant))
        }

        if let bottom = bottom {
            anchors.append(bottomAnchor.constraint(equalTo: bottom, constant: -bottomConstant))
        }

        if let right = right {
            anchors.append(rightAnchor.constraint(equalTo: right, constant: -rightConstant))
        }

        if widthConstant > 0 {
            anchors.append(widthAnchor.constraint(equalToConstant: widthConstant))
        }

        if heightConstant > 0 {
            anchors.append(heightAnchor.constraint(equalToConstant: heightConstant))
        }

        anchors.forEach({$0.isActive = true})

        return anchors
    }

    @objc public func anchorCenterXToSuperview(constant: CGFloat = 0) {
        translatesAutoresizingMaskIntoConstraints = false
        if let anchor = superview?.centerXAnchor {
            centerXAnchor.constraint(equalTo: anchor, constant: constant).isActive = true
        }
    }

    @objc public func anchorCenterYToSuperview(constant: CGFloat = 0) {
        translatesAutoresizingMaskIntoConstraints = false
        if let anchor = superview?.centerYAnchor {
            centerYAnchor.constraint(equalTo: anchor, constant: constant).isActive = true
        }
    }

    @objc public func anchorCenterSuperview() {
        anchorCenterXToSuperview()
        anchorCenterYToSuperview()
    }

    @nonobjc func add(_ views: UIView...) {
        views.forEach { self.addSubview($0) }
    }
}

extension UIView {

    @objc var safeTopAnchor: NSLayoutYAxisAnchor {
        if #available(iOS 11.0, *) {
            return self.safeAreaLayoutGuide.topAnchor
        } else {
            return self.topAnchor
        }
    }

    @objc var safeLeftAnchor: NSLayoutXAxisAnchor {
        if #available(iOS 11.0, *){
            return self.safeAreaLayoutGuide.leftAnchor
        }else {
            return self.leftAnchor
        }
    }

    @objc var safeRightAnchor: NSLayoutXAxisAnchor {
        if #available(iOS 11.0, *){
            return self.safeAreaLayoutGuide.rightAnchor
        }else {
            return self.rightAnchor
        }
    }

    @objc var safeBottomAnchor: NSLayoutYAxisAnchor {
        if #available(iOS 11.0, *) {
            return self.safeAreaLayoutGuide.bottomAnchor
        } else {
            return self.bottomAnchor
        }
    }
}