Playing with Layout Constraints and VFL in Swift Playground

ConstraintsInPlayground.swift

// playing with Xcode, Constraints and Playground

import UIKit
import XCPlayground

let hostView = UIView()
hostView.frame = CGRectMake(0, 0, 400, 200)
hostView.backgroundColor = UIColor.lightGrayColor()

XCPlaygroundPage.currentPage.liveView = hostView

let label = UILabel(frame: .zero)
label.translatesAutoresizingMaskIntoConstraints = false
label.backgroundColor = UIColor.greenColor()
label.text = "I am a label"

hostView.addSubview(label)

let views = ["label": label]

var constraints = [NSLayoutConstraint]()
constraints += NSLayoutConstraint.constraintsWithVisualFormat("H:|-25-[label]-25-|", options: [], metrics: nil, views:views)
constraints += NSLayoutConstraint.constraintsWithVisualFormat("V:|-25-[label]-25-|", options: [], metrics: nil, views:views)

NSLayoutConstraint.activateConstraints(constraints)