Auto layout in playground

gistfile1.txt

// Auto layout in a Swift Playground (for iOS).

import UIKit

var v = UIView()
v.frame = CGRectMake(0, 0, 200, 200)

var b1 = UIButton()
b1.setTitle("Click Me", forState:UIControlState.Normal)
b1.setTitleColor(UIColor.blueColor(), forState: UIControlState.Normal)
b1.setTranslatesAutoresizingMaskIntoConstraints(false)
v.addSubview(b1)

var b2 = UIButton()
b2.setTitle("Click Me Too", forState:UIControlState.Normal)
b2.setTitleColor(UIColor.blueColor(), forState: UIControlState.Normal)
b2.setTranslatesAutoresizingMaskIntoConstraints(false)
v.addSubview(b2)

var views = Dictionary<String, UIView>()
views["b1"] = b1
views["b2"] = b2

v.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-[b1]-|", options: nil, metrics: nil, views: views))

v.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-[b2]-|", options: nil, metrics: nil, views: views))

v.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-[b1]-[b2]", options: nil, metrics: nil, views: views))

v.layoutIfNeeded()

b1.frame
b2.frame
v.frame

v

You can set the Platform (iOS or OS X) in the file explorer: View -> Utilities -> Show File Explorer