InteractivePlayground with button that prints hello (swift 3.0.1)

playground.swift

import AppKit
import XCPlayground
import Cocoa
import PlaygroundSupport

extension NSLayoutConstraint {
    convenience init(view item: NSView, to toItem: NSView, attribute: NSLayoutAttribute, constant c: CGFloat = 0) {
        self.init(item: item, attribute: attribute,
                  relatedBy: .equal,
                  toItem: toItem, attribute: attribute,
                  multiplier: 1.0, constant: c)
        self.isActive = true
        self.shouldBeArchived = true
        item.translatesAutoresizingMaskIntoConstraints = false
    }
}

let viewRect = NSRect(x: 0, y: 0, width: 300, height: 200)
var view = NSView(frame: viewRect)

view.wantsLayer = true


class Test: NSObject {
    @objc func test(sender: AnyObject) {
        Swift.print("Hallo")
    }
}

let t = Test()

var button: NSButton = {
    $0.title = "Hallo"
    $0.target = t
    $0.action = #selector(t.test)
    $0.isEnabled = true
    $0.bezelStyle = .rounded
    return $0
}(NSButton(frame: NSRect(x: 0, y: 0, width: 100, height: 30)))

view.addSubview(button)

PlaygroundPage.current.liveView = view
//PlaygroundPage.current.needsIndefiniteExecution = true
NSLayoutConstraint(view: button, to: view, attribute: .centerX)
NSLayoutConstraint(view: button, to: view, attribute: .centerY)