A small extension to make creating UIView anchors less painful

UIView+extension.swift

//
//  UIView+extension.swift
//
//  Created by Noah Tsutsui on 7/25/18.
//  Copyright © 2018 Noah Tsutsui. All rights reserved.

//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.
//

import UIKit

extension UIView {
  func anchor(horizontalCenter: Bool, horizontalCenterAnchor: NSLayoutXAxisAnchor?, verticalCenter: Bool, verticalCenterAnchor: NSLayoutYAxisAnchor?, leadingAnchor: NSLayoutXAxisAnchor?, trailingAnchor: NSLayoutXAxisAnchor?, topAnchor: NSLayoutYAxisAnchor?, rightAnchor: NSLayoutXAxisAnchor?, bottomAnchor: NSLayoutYAxisAnchor?, leftAnchor: NSLayoutXAxisAnchor?, width: CGFloat?, height: CGFloat?, topPadding: CGFloat, rightPadding: CGFloat, bottomPadding: CGFloat, leftPadding: CGFloat){
    self.translatesAutoresizingMaskIntoConstraints = false
    
    if horizontalCenter {
      if let horizontalCenterAnchor = horizontalCenterAnchor {
        
        self.centerXAnchor.constraint(equalTo: horizontalCenterAnchor, constant: leftPadding+rightPadding).isActive = true
        
        if rightAnchor != nil || leftAnchor != nil || leadingAnchor != nil || trailingAnchor != nil {
          print("You have set horizontal centerting in addition to left/right/leading/trailing anchor(s). Is this intentional?")
        }
      }
    }
    
    if leftAnchor != nil && leadingAnchor != nil {
      print("You have both a leading and left anchor, you can only use one. Probably a verbose warning from XCode is below?")
    }
    
    if trailingAnchor != nil && rightAnchor != nil {
      print("You have both a tailing and right anchor, you can only use one. Probably a verbose warning from XCode is below?")
    }
    
    if let rightAnchor = rightAnchor {
      self.rightAnchor.constraint(equalTo: rightAnchor, constant: -rightPadding).isActive = true
    }
    if let leftAnchor = leftAnchor {
      self.leftAnchor.constraint(equalTo: leftAnchor, constant: leftPadding).isActive = true
    }
    if let leadingAnchor = leadingAnchor {
      self.leadingAnchor.constraint(equalTo: leadingAnchor, constant: leftPadding).isActive = true
    }
    if let trailingAnchor = trailingAnchor {
      self.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -rightPadding).isActive = true
    }
    
    if verticalCenter {
      if let verticalCenterAnchor = verticalCenterAnchor {
        self.centerYAnchor.constraint(equalTo: verticalCenterAnchor, constant: topPadding + bottomPadding).isActive = true
        
        if topAnchor != nil || bottomAnchor != nil {
          print("You have either top or bottom anchor in addition to centerYAnchor, is this intentional?")
        }
      }
    }
    
    if let topAnchor = topAnchor {
      self.topAnchor.constraint(equalTo: topAnchor, constant: topPadding).isActive = true
    }
    if let bottomAnchor = bottomAnchor {
      self.bottomAnchor.constraint(equalTo: bottomAnchor, constant: bottomPadding).isActive = true
    }
    
    
    if let width = width {
       if width > 0 {
            self.widthAnchor.constraint(equalToConstant: width).isActive = true
        }
    }
    if let height = height {
        if height > 0 {
            self.heightAnchor.constraint(equalToConstant: height).isActive = true
        }
    }
  }
}

Better UIView Anchors

A simple UIView extension that makes anchors suck less.

Looks like...

func anchor(
  horizontalCenter: Bool, 
  horizontalCenterAnchor: NSLayoutXAxisAnchor?, 
  verticalCenter: Bool, 
  verticalCenterAnchor: NSLayoutYAxisAnchor?, 
  leadingAnchor: NSLayoutXAxisAnchor?, 
  trailingAnchor: NSLayoutXAxisAnchor?, 
  topAnchor: NSLayoutYAxisAnchor?, 
  rightAnchor: NSLayoutXAxisAnchor?, 
  bottomAnchor: NSLayoutYAxisAnchor?, 
  leftAnchor: NSLayoutXAxisAnchor?, 
  width: CGFloat?, 
  height: CGFloat?, 
  topPadding: CGFloat, 
  rightPadding: CGFloat, 
  bottomPadding: CGFloat, 
  leftPadding: CGFloat
)

Cool things

Automatically applies isActive = true and translatesAutoresizingMaskIntoConstraints = false

More friendly warnings when...

• Attempting to apply left/right and leading/trailing at the same time.
• Attempting to apply a top/bottom anchor to a centerYAnchor, of
  likewise, a left/right/leading/trailing anchor to a centerXAnchor.

Usage

Simply place UIView+Extension.swift in your project or append to the bottom of your ViewController.

Now you can:

myBeautifulView.anchor(
  horizontalCenter: true, 
  horizontalCenterAnchor: view.safeAreaLayoutGuide.centerXAnchor, 
  verticalCenter: false, 
  verticalCenterAnchor: nil, 
  leadingAnchor: nil, 
  trailingAnchor: nil, 
  topAnchor: view.safeAreaLayoutGuide.topAnchor, 
  rightAnchor: nil, 
  bottomAnchor: nil, 
  leftAnchor: nil, 
  width: 140, 
  height: 140, 
  topPadding: 40, 
  rightPadding: 0, 
  bottomPadding: 0, 
  leftPadding: 0
)