Programmatically Added Constraint Not Working

Question

I\'ve been trying to add constraints programmatically to a view that I\'m also adding programmatically to my view controller. However, it seems like the constraints are not

Answer 1

set translatesAutoresizingMaskIntoConstraints = false to any view you are settings constraints programatically.

from the apple doc:
translatesAutoresizingMaskIntoConstraints

If you want to use Auto Layout to dynamically calculate the size and position of your view, you must set this property to false, and then provide a non ambiguous, nonconflicting set of constraints for the view.

Answer 2

You don't set all necessary constraints, that can be the reason. Consider following rough example. MyView interface is defined in standalone xib file. Hope it helps:

 class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        guard let myView = loadFromNib("MyView") else {
            return
        }

        view.addSubview(myView)

        myView.translatesAutoresizingMaskIntoConstraints = false
        view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-15-[myView]-15-|", options: NSLayoutFormatOptions.DirectionLeadingToTrailing, metrics: nil, views: ["myView": myView]))

        view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-15-[myView]-15-|", options: NSLayoutFormatOptions.DirectionLeadingToTrailing, metrics: nil, views: ["myView": myView]))
    }

    func loadFromNib(cls: String) -> UIView? {

        return  NSBundle.mainBundle().loadNibNamed(cls, owner: nil, options: nil)[0] as? UIView
    }
}