[iOS] How to make UI parts added from code fit in Safe Area

manner

Prior to iOS 11, use a combination of topLayoutGuide and bottomLayoutGuide. For iOS 11 or later, it is integrated into the SafeAreaLayoutGuide, so use that.

ExampleViewController.swift

private let greenView = UIView()

private func setupView() {
  greenView.translatesAutoresizingMaskIntoConstraints = false
  greenView.backgroundColor = .green
  view.addSubview(greenView)

  let margins = view.layoutMarginsGuide
  NSLayoutConstraint.activate([
    greenView.leadingAnchor.constraint(equalTo: margins.leadingAnchor),
    greenView.trailingAnchor.constraint(equalTo: margins.trailingAnchor)
    ])

  if #available(iOS 11, *) {
    let guide = view.safeAreaLayoutGuide
    NSLayoutConstraint.activate([
     greenView.topAnchor.constraintEqualToSystemSpacingBelow(guide.topAnchor, multiplier: 1.0),
     guide.bottomAnchor.constraintEqualToSystemSpacingBelow(greenView.bottomAnchor, multiplier: 1.0)
     ])
  } else {
     let standardSpacing: CGFloat = 8.0
     NSLayoutConstraint.activate([
     greenView.topAnchor.constraint(equalTo: topLayoutGuide.bottomAnchor, constant: standardSpacing),
     bottomLayoutGuide.topAnchor.constraint(equalTo: greenView.bottomAnchor, constant: standardSpacing)
     ])
  }

If you are not using AutoLayout, you can get the margin value of the safeArea part from safeAreaInsets, and if it is less than iOS11, you can get it from topLayoutGuide.length, bottomLayoutGuide.length.

reference

iPhone X compatible ~ outside Safe Area ~ Positioning Content Relative to the Safe Area USE YOUR LOAF - Safe Area Layout Guide Stack Overflow - How do I use Safe Area Layout programmatically?