playground で非同期通信をする ref: http://qiita.com/ezura/items/b17fec1240654028d265

file0.swift

import XCPlayground

file2.swift

XCPSetExecutionShouldContinueIndefinitely()

例

NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue()) { (response, data, error) -> Void in
  何か処理
}