//https://stackoverflow.com/a/26181982/13171606
//There are multiple ways to add contraints, please open Link for almost ecery type of constraint
override func viewDidLoad() { let newView = UIView() newView.backgroundColor = UIColor.red view.addSubview(newView) newView.translatesAutoresizingMaskIntoConstraints = false//compulsory newView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true newView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true newView.widthAnchor.constraint(equalToConstant: 100).isActive = true newView.heightAnchor.constraint(equalToConstant: 100).isActive = true
}

fileprivate func setupName() { lblName.text = "Hello world" // Step 1 lblName.translatesAutoresizingMaskIntoConstraints = false //Step 2 self.view.addSubview(lblName) //Step 3 NSLayoutConstraint.activate([ lblName.centerXAnchor.constraint(equalTo: self.view.centerXAnchor), lblName.centerYAnchor.constraint(equalTo: self.view.centerYAnchor) ])
}

import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let myImageView:UIImageView = UIImageView()
myImageView.backgroundColor = UIColor.red
myImageView.image = UIImage(named:"sample_dog")!
myImageView.translatesAutoresizingMaskIntoConstraints = false
myImageView.layer.borderColor = UIColor.red.cgColor
myImageView.layer.borderWidth = 10
self.view.addSubview(myImageView)
view.removeConstraints(view.constraints)
view.addConstraint(NSLayoutConstraint(
item: myImageView,
attribute: .top,
relatedBy: .equal,
toItem: view,
attribute: .top,
multiplier: 1,
constant:100)
)
view.addConstraint(NSLayoutConstraint(
item: myImageView,
attribute: .centerX,
relatedBy: .equal,
toItem: view,
attribute: .centerX,
multiplier: 1,
constant:0)
)
view.addConstraint(NSLayoutConstraint(
item: myImageView,
attribute: .height,
relatedBy: .equal,
toItem: view,
attribute: .width,
multiplier: 0.5,
constant:40))
view.addConstraint(NSLayoutConstraint(
item: myImageView,
attribute: .width,
relatedBy: .equal,
toItem: view,
attribute: .width,
multiplier: 0.5,
constant:40))
}
override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning()
}
}

 - firstView.coverWholeSuperview() - firstView.constraints(size: CGSize(width: 44, height: 44), centerX: view.centerXAnchor, centerY: view.centerXAnchor) - firstView.constraints(top: view.topAnchor, leading: secondView.leadingAnchor, bottom: view.bottomAnchor, trailing: secondView.trailingAnchor, padding: UIEdgeInsets(top: 12, left: 12, bottom: 12, right: 12))

//create a generic function with type constraint
func addition<T: Numeric>(num1: T, num2: T) { print("Sum:", num1 + num2)
}
// pass Int value
addition(num1: 5, num2: 10)
// pass Double value
addition(num1: 5.5, num2: 10.8)

 /*
// regular use
1.leftAnchor
2.rightAnchor
3.topAnchor
// intermediate use
4.widthAnchor
5.heightAnchor
6.bottomAnchor
7.centerXAnchor
8.centerYAnchor
// rare use
9.leadingAnchor
10.trailingAnchor
etc. (note: very project to project)
*/