UILayoutGuide_Container.swift

UILayoutGuide_Container.swift

class ViewController: UIViewController {

    let container = UILayoutGuide()

    override func viewDidLoad() {
        super.viewDidLoad()

        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        label.text = "Swift"
        view.addSubview(label)

        let textField = UITextField()
        textField.translatesAutoresizingMaskIntoConstraints = false
        textField.text = "Language"
        view.addSubview(textField)

        view.addLayoutGuide(container)

        // Set interior constraints
        label.lastBaselineAnchor.constraintEqualToAnchor(textField.lastBaselineAnchor).active = true

        label.leadingAnchor.constraintEqualToAnchor(container.leadingAnchor).active = true

        textField.leadingAnchor.constraintEqualToAnchor(label.trailingAnchor, constant: 8.0).active = true
        textField.trailingAnchor.constraintEqualToAnchor(container.trailingAnchor).active = true
        textField.topAnchor.constraintEqualToAnchor(container.topAnchor).active = true
        textField.bottomAnchor.constraintEqualToAnchor(container.bottomAnchor).active = true

        // Set exterior constraints
        // The contents of the container can be treated as a black box
        let margins = view.layoutMarginsGuide

        container.leadingAnchor.constraintEqualToAnchor(margins.leadingAnchor).active = true
        container.trailingAnchor.constraintEqualToAnchor(margins.trailingAnchor).active = true

        // Must use NSLayoutConstraint with the scene's top and bottom layout guides.
        NSLayoutConstraint(item: container,
            attribute: .Top,
            relatedBy: .Equal,
            toItem: topLayoutGuide,
            attribute: .Bottom,
            multiplier: 1.0,
            constant: 20.0).active = true
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()

        print(container.layoutFrame)
    }
}