UIViewAutoLayoutExtensions.swift

import UIKit

// MARK: - SafeArea Extensions
extension UIView {
    
    var safeTopAnchor: NSLayoutYAxisAnchor {
        if #available(iOS 11.0, *) {
            return self.safeAreaLayoutGuide.topAnchor
        }
        return self.topAnchor
    }
    
    var safeLeadingAnchor: NSLayoutXAxisAnchor {
        if #available(iOS 11.0, *) {
            return self.safeAreaLayoutGuide.leadingAnchor
        }
        return self.leadingAnchor
    }
    
    var safeTrailingAnchor: NSLayoutXAxisAnchor {
        if #available(iOS 11.0, *) {
            return self.safeAreaLayoutGuide.trailingAnchor
        }
        return self.trailingAnchor
    }
    
    var safeBottomAnchor: NSLayoutYAxisAnchor {
        if #available(iOS 11.0, *) {
            return self.safeAreaLayoutGuide.bottomAnchor
        }
        return self.bottomAnchor
    }
    
    func safeBoundInside(superView: UIView, inset: UIEdgeInsets = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)) {
        self.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            self.safeLeadingAnchor.constraint(equalTo: superView.safeLeadingAnchor, constant: inset.left),
            superView.safeTrailingAnchor.constraint(equalTo: self.safeTrailingAnchor, constant: inset.right),
            self.safeTopAnchor.constraint(equalTo: superView.safeTopAnchor, constant: inset.top),
            superView.safeBottomAnchor.constraint(equalTo: self.safeBottomAnchor, constant: inset.bottom)
        ])
    }
    
}

// MARK: - VFL Extensions
extension UIView {
    
    func addConstraintsWithFormat(
        format: String, views: UIView...,
        options: NSLayoutConstraint.FormatOptions = NSLayoutConstraint.FormatOptions()) {
        
        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: options, metrics: nil, views: viewsDictionary))
    }
    
    func boundInside(superView: UIView,
                           inset: UIEdgeInsets = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0),
                           unpin: UIRectEdge = []) {
        
        self.translatesAutoresizingMaskIntoConstraints = false
        
        let leftUnpin = (unpin == .left) ? ">=" : ""
        let rightUnpin = (unpin == .right) ? ">=" : ""
        let topUnpin = (unpin == .top) ? ">=" : ""
        let bottomUnpin = (unpin == .bottom) ? ">=" : ""
        
        superView.addConstraints(
            NSLayoutConstraint.constraints(
                withVisualFormat: "H:|-(\(leftUnpin)\(inset.left))-[subview]-(\(rightUnpin)\(inset.right))-|",
                options: NSLayoutConstraint.FormatOptions.directionLeadingToTrailing,
                metrics: nil, views: ["subview": self])
        )
        superView.addConstraints(
            NSLayoutConstraint.constraints(withVisualFormat: "V:|-(\(topUnpin)\(inset.top))-[subview]-(\(bottomUnpin)\(inset.bottom))-|",
                options: NSLayoutConstraint.FormatOptions.directionLeadingToTrailing,
                metrics: nil, views: ["subview": self])
        )
        
    }
    
}