How to set an element center of view programmatically in iOS Swift 3?

Question

I have a view and I want to center it horizontally and vertically in its superview.

I tried this but it's not working:

let horConstraint = NSLayoutConstraint(item: webView, attribute: .leading, relatedBy: .equal, toItem: view, attribute: .leading, multiplier: 1.0, constant: 0.0)
view.addConstraints([horConstraint]) 

Answer 1

I would suggest trying to use Anchors which are more convenient and easy to understand. This code centered my view:

    let someView = UIView()
    someView.backgroundColor = .red
    someView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(someView)
    NSLayoutConstraint.activate([
        someView.centerXAnchor.constraint(equalTo: view.centerXAnchor),
        someView.centerYAnchor.constraint(equalTo: view.centerYAnchor),
        someView.heightAnchor.constraint(equalToConstant: 50),
        someView.widthAnchor.constraint(equalToConstant: 50)
    ])