오토레이아웃을 코드로 작성하는 방법은 무엇인가? (3가지)

// Get the superview's layout
let margins = view.layoutMarginsGuide
 
// Pin the leading edge of myView to the margin's leading edge
myView.leadingAnchor.constraint(equalTo: margins.leadingAnchor).isActive = true
 
// Pin the trailing edge of myView to the margin's trailing edge
myView.trailingAnchor.constraint(equalTo: margins.trailingAnchor).isActive = true
 
// Give myView a 1:2 aspect ratio
myView.heightAnchor.constraint(equalTo: myView.widthAnchor, multiplier: 2.0).isActive = true

NSLayoutConstraint(item: myView, attribute: .leading, relatedBy: .equal, toItem: view, attribute: .leadingMargin, multiplier: 1.0, constant: 0.0).isActive = true
 
NSLayoutConstraint(item: myView, attribute: .trailing, relatedBy: .equal, toItem: view, attribute: .trailingMargin, multiplier: 1.0, constant: 0.0).isActive = true
 
NSLayoutConstraint(item: myView, attribute: .height, relatedBy: .equal, toItem: myView, attribute:.width, multiplier: 2.0, constant:0.0).isActive = true

let views = ["myView" : myView]
let formatString = "|-[myView]-|"
 
let constraints = NSLayoutConstraint.constraints(withVisualFormat: formatString, options: .alignAllTop, metrics: nil, views: views)
 
NSLayoutConstraint.activate(constraints)