override func viewDidLoad() {

    let newView = UIView()

    newView.backgroundColor = UIColor.red

    view.addSubview(newView)

​

    newView.translatesAutoresizingMaskIntoConstraints = false

    let views = ["newView": newView]

    let widthConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[newView(100)]", options: NSLayoutConstraint.FormatOptions(rawValue: 0), metrics: nil, views: views)

    let heightConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[newView(100)]", options: NSLayoutConstraint.FormatOptions(rawValue: 0), metrics: nil, views: views)

    let horizontalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerX, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerX, multiplier: 1, constant: 0)

    let verticalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerY, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerY, multiplier: 1, constant: 0)

    view.addConstraints(widthConstraints)

    view.addConstraints(heightConstraints)

    view.addConstraints([horizontalConstraint, verticalConstraint])

}

override func viewDidLoad() {

    let newView = UIView()

    newView.backgroundColor = UIColor.red

    view.addSubview(newView)

​

    newView.translatesAutoresizingMaskIntoConstraints = false

    let horizontalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerX, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerX, multiplier: 1, constant: 0)

    let verticalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerY, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerY, multiplier: 1, constant: 0)

    let widthConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.width, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: NSLayoutConstraint.Attribute.notAnAttribute, multiplier: 1, constant: 100)

    let heightConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.height, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: NSLayoutConstraint.Attribute.notAnAttribute, multiplier: 1, constant: 100)

    view.addConstraints([horizontalConstraint, verticalConstraint, widthConstraint, heightConstraint])

}

override func viewDidLoad() {

    let newView = UIView()

    newView.backgroundColor = UIColor.red

    view.addSubview(newView)

​

    newView.translatesAutoresizingMaskIntoConstraints = false

    let horizontalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerX, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerX, multiplier: 1, constant: 0)

    let verticalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerY, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerY, multiplier: 1, constant: 0)

    let widthConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.width, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: NSLayoutConstraint.Attribute.notAnAttribute, multiplier: 1, constant: 100)

    let heightConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.height, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: NSLayoutConstraint.Attribute.notAnAttribute, multiplier: 1, constant: 100)

    NSLayoutConstraint.activate([horizontalConstraint, verticalConstraint, widthConstraint, heightConstraint])

}

override func viewDidLoad() {

    let newView = UIView()

    newView.backgroundColor = UIColor.red

    view.addSubview(newView)

​

    newView.translatesAutoresizingMaskIntoConstraints = false

    NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerX, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerX, multiplier: 1, constant: 0).isActive = true

    NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerY, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerY, multiplier: 1, constant: 0).isActive = true

    NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.width, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: NSLayoutConstraint.Attribute.notAnAttribute, multiplier: 1, constant: 100).isActive = true

    NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.height, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: NSLayoutConstraint.Attribute.notAnAttribute, multiplier: 1, constant: 100).isActive = true

}

override func viewDidLoad() {

    let newView = UIView()

    newView.backgroundColor = UIColor.red

    view.addSubview(newView)

​

    newView.translatesAutoresizingMaskIntoConstraints = false

    let views = ["view": view!, "newView": newView]

    let horizontalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[view]-(<=0)-[newView(100)]", options: NSLayoutConstraint.FormatOptions.alignAllCenterY, metrics: nil, views: views)

    let verticalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[view]-(<=0)-[newView(100)]", options: NSLayoutConstraint.FormatOptions.alignAllCenterX, metrics: nil, views: views)

    view.addConstraints(horizontalConstraints)

    view.addConstraints(verticalConstraints)

}

override func viewDidLoad() {

    let newView = UIView()

    newView.backgroundColor = UIColor.red

    view.addSubview(newView)

​

    newView.translatesAutoresizingMaskIntoConstraints = false

    let views = ["view": view!, "newView": newView]

    let horizontalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[view]-(<=0)-[newView(100)]", options: NSLayoutConstraint.FormatOptions.alignAllCenterY, metrics: nil, views: views)

    let verticalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[view]-(<=0)-[newView(100)]", options: NSLayoutConstraint.FormatOptions.alignAllCenterX, metrics: nil, views: views)

    NSLayoutConstraint.activate(horizontalConstraints)

    NSLayoutConstraint.activate(verticalConstraints)

}