Doing iOS UI in code with SnapKit

iOS-UI-in-code-with-SnapKit.swift

import UIKit
import SnapKit

class SomeViewController: UIViewController {
  var addButton = UIButton()
  var helloWorldLabel = UILabel()
  
  override func viewDidLoad() {
    let superView = view
    let views = [
      addButton,
      helloWorldLabel,
    ]
    
    views.map { superView.addSubview($0) }
    
    addButton.snp_makeConstraints { (make) -> Void in
      // Centered vertically + As wide as the super view
      make.centerY.left.right.equalTo(superView)
    }
    
    helloWorldLabel.snp_makeConstraints { (make) -> Void in
      // As wide as the super view
      make.left.right.equalTo(superView)
      // Put it on the top of addButton
      make.bottom.equalTo(addButton.snp_top)
    }
  }
}