NSLayout Constraints

nslayoutconstraint.swift

private func setupNSLayoutConstraints() {
    view.addSubview(titleLabel)
    view.addSubview(hiButton)

    let labelVerticalConstraint = NSLayoutConstraint.init(item: titleLabel, attribute: .top, relatedBy: .equal, toItem: view, attribute: .top, multiplier: 1, constant: 20)
    let labelLeadingConstraint = NSLayoutConstraint.init(item: titleLabel, attribute: .leading, relatedBy: .equal, toItem: view, attribute: .leading, multiplier: 1, constant: 20)
    let labelTrailingConstraint = NSLayoutConstraint.init(item: titleLabel, attribute: .trailing, relatedBy: .equal, toItem: view, attribute: .trailing, multiplier: 1, constant: -20)

    let buttonVerticalConstraint = NSLayoutConstraint.init(item: hiButton, attribute: .top, relatedBy: .equal, toItem: titleLabel, attribute: .bottom, multiplier: 1, constant: 8)
    let buttonLeadingConstraint = NSLayoutConstraint.init(item: hiButton, attribute: .leading, relatedBy: .equal, toItem: view, attribute: .leading, multiplier: 1, constant: 20)
    let buttonTrailingConstraint = NSLayoutConstraint.init(item: hiButton, attribute: .trailing, relatedBy: .equal, toItem: view, attribute: .trailing, multiplier: 1, constant: -20)

    view.addConstraints([
        labelVerticalConstraint,
        labelLeadingConstraint,
        labelTrailingConstraint,
        buttonVerticalConstraint,
        buttonLeadingConstraint,
        buttonTrailingConstraint
    ])
}