Extension for UIView making AutoLayout a breeze

UIView+AutoLayout.swift

//
//  UIView+AutoLayout.swift
//
//  Created by Zhendryk on 10/24/18.
//  Copyright © 2018 Zhendryk. All rights reserved.
//

import UIKit

extension UIView {

    /// Returns the parent UIViewController of this UIView if it exists
    var parentViewController: UIViewController? {
        var parentResponder: UIResponder? = self
        while parentResponder != nil {
            parentResponder = parentResponder!.next
            if let viewController = parentResponder as? UIViewController {
                return viewController
            }
        }
        return nil
    }
    
    /// Enables AutoLayout for this UIView
    func enableAutoLayout() {
        translatesAutoresizingMaskIntoConstraints = false
    }
    
    /// Disables AutoLayout for this UIView
    func disableAutoLayout() {
        translatesAutoresizingMaskIntoConstraints = true
    }
    
    /// Anchors this UIView to the given NSLayoutAxisAnchors with optional padding and size
    ///
    /// - Parameters:
    ///   - top: The NSLayoutYAxisAnchor to anchor the top edge of this UIView to
    ///   - leading: The NSLayoutXAxisAnchor to anchor the leading (left) edge of this UIView to
    ///   - bottom: The NSLayoutYAxisAnchor to anchor the bottom edge of this UIView to
    ///   - trailing: The NSLayoutXAxisAnchor to anchor the trailing (right) edge of this UIView to
    ///   - padding: UIEdgeInsets describing the padding you want on the edges of this UIView
    ///   - size: The height and width you want this UIView to be
    func anchor(top: NSLayoutYAxisAnchor?, leading: NSLayoutXAxisAnchor?, bottom: NSLayoutYAxisAnchor?, trailing: NSLayoutXAxisAnchor?, padding: UIEdgeInsets = .zero, size: CGSize = .zero) {
        if let top = top {
            topAnchor.constraint(equalTo: top, constant: padding.top).isActive = true
        }
        
        if let leading = leading {
            leadingAnchor.constraint(equalTo: leading, constant: padding.left).isActive = true
        }
        
        if let bottom = bottom {
            bottomAnchor.constraint(equalTo: bottom, constant: -padding.bottom).isActive = true
        }
        
        if let trailing = trailing {
            trailingAnchor.constraint(equalTo: trailing, constant: -padding.right).isActive = true
        }
        
        if size.width != 0 {
            widthAnchor.constraint(equalToConstant: size.width).isActive = true
        }
        
        if size.height != 0 {
            heightAnchor.constraint(equalToConstant: size.height).isActive = true
        }
    }
    
    
    /// Sets the height and width anchors of this UIView equal to the height and width anchors of the given UIView
    ///
    /// - Parameter view: The view to set the size of this UIView equal to
    func anchorEqualSize(to view: UIView) {
        widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true
        heightAnchor.constraint(equalTo: view.heightAnchor).isActive = true
    }
    
    /// Constraints the width and height of this UIView to the given size
    ///
    /// - Parameter size: The size to constrain this UIView to
    func anchorConstantSize(size: CGSize) {
        widthAnchor.constraint(equalToConstant: size.width).isActive = true
        heightAnchor.constraint(equalToConstant: size.height).isActive = true
    }
    
    /// Sets the height and width anchors of this UIView equal to the height and width anchors of the given UIView multiplied by the given scale for each
    ///
    /// - Parameters:
    ///   - view: The view to set the proportional size of this UIView to
    ///   - widthMultiplier: The scale relative to the given UIView for this UIView's width
    ///   - heightMultiplier: The scale relative to the given UIView for this UIView's height
    func anchorProportionalSize(to view: UIView, widthMultiplier: CGFloat = 0, heightMultiplier: CGFloat = 0) {
        if widthMultiplier != 0 {
            widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: widthMultiplier).isActive = true
        }
        if heightMultiplier != 0 {
            heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: heightMultiplier).isActive = true
        }
    }
    
    /// Constrains this UIView to a square of the given proportional width to the given UIView
    ///
    /// - Parameters:
    ///   - view: The view to reference for the proportional size
    ///   - widthMultiplier: The scaled width of this UIView relative to the given UIView
    func anchorProportionalSquare(to view: UIView, widthMultiplier: CGFloat) {
        self.anchorProportionalSize(to: view, widthMultiplier: widthMultiplier)
        self.anchorHeightToWidth()
    }
    
    /// Anchors the width of this UIView equal to the height
    func anchorWidthToHeight() {
        widthAnchor.constraint(equalTo: heightAnchor).isActive = true
    }
    
    /// Anchors the height of this UIView equal to the width
    func anchorHeightToWidth(){
        heightAnchor.constraint(equalTo: widthAnchor).isActive = true
    }
    
    /// Expands this UIView to fill its container with optional padding
    ///
    /// - Parameter padding: The amount of padding around each edge of this UIView
    func fillSuperview(_ padding: UIEdgeInsets = .zero) {
        anchor(top: superview?.topAnchor, leading: superview?.leadingAnchor, bottom: superview?.bottomAnchor, trailing: superview?.trailingAnchor, padding: padding)
    }
    
    /// Aligns the center of this UIView to the center of its superview if it exists
    func alignCenterPointToSuperView() {
        if let superCenter = superview?.center {
            center = superCenter
        }
    }
    
    /// Aligns both the centerYAnchor and centerXAnchor of this UIView to its superview if it exists
    func centerInSuperview() {
        if let superCenterX = superview?.centerXAnchor {
            centerXAnchor.constraint(equalTo: superCenterX).isActive = true
        }
        if let superCenterY = superview?.centerYAnchor {
            centerYAnchor.constraint(equalTo: superCenterY).isActive = true
        }
    }
    
    /// Aligns the centerYAnchor of this UIView to its superview if it exists
    func centerVerticallyInSuperview() {
        if let superCenterY = superview?.centerYAnchor {
            centerYAnchor.constraint(equalTo: superCenterY).isActive = true
        }
    }
    
    /// Aligns the centerXAnchor of this UIView to its superview if it exists
    func centerHorizontallyInSuperview() {
        if let superCenterX = superview?.centerXAnchor {
            centerXAnchor.constraint(equalTo: superCenterX).isActive = true
        }
    }
}