Safe Area Insets

SafeAreaInsets.swift

import UIKit

class ViewController: UIViewController {

    let wrapperView = UIView()
    let cyanView = UIView()

    override func viewDidLoad() {
        view.backgroundColor = .green
        view.addSubview(wrapperView)
        wrapperView.addSubview(cyanView)

        wrapperView.backgroundColor = .red
        wrapperView.translatesAutoresizingMaskIntoConstraints = false

        cyanView.backgroundColor = .cyan
        cyanView.translatesAutoresizingMaskIntoConstraints = false
    }

    override func viewDidLayoutSubviews() {
        wrapperView.frame = CGRect(x: view.frame.origin.x,
                                   y: view.safeAreaInsets.top,
                                   width: view.frame.size.width,
                                   height: view.frame.size.height - view.safeAreaInsets.top)

        cyanView.frame = CGRect(x: wrapperView.layoutMargins.left,
                                y: wrapperView.layoutMargins.top,
                                width: wrapperView.frame.size.width - wrapperView.layoutMargins.left-wrapperView.layoutMargins.right,
                                height: 100)
    }
}