title: NSOperationQueue addOperations waitUntilFinished
body: <p>Hi I am building an app using Swift. I need to process notifications in a specific order. Therefore I am trying to use addOperations waitUntilFinished. </p>
  
  <p>Here is what I did:</p>
  
  <pre><code>let oldify = NSOperation()
      oldify.completionBlock = {
  println("oldify")
  }
  let appendify = NSOperation()
      appendify.completionBlock = {
  println("appendify")
  }
  let nettoyify = NSOperation()
      nettoyify.completionBlock = {
  println("nettoyify")
  }
  NSOperationQueue.mainQueue().maxConcurrentOperationCount = 1
  NSOperationQueue.mainQueue().addOperations([oldify, appendify, nettoyify], waitUntilFinished: true)
  </code></pre>
  
  <p>With this code none of the operations is being executed. When I try this instead:</p>
  
  <pre><code>NSOperationQueue.mainQueue().maxConcurrentOperationCount = 1
  NSOperationQueue.mainQueue().addOperation(oldify)
  NSOperationQueue.mainQueue().addOperation(appendify)
  NSOperationQueue.mainQueue().addOperation(nettoyify)
  </code></pre>
  
  <p>The operations get executed but not in the right order.</p>
  
  <p>Does anyone know what I'm doing wrong? I am getting confident in swift but completely new to NSOperations</p>