title: Assistant Editor shows different "ViewController.swift" file than the one that Main Editor shows?
body: <p>The source code shown in the <em>Assistant Editor</em> for "ViewController.swift" is different than source code shown in <em>Main Editor</em> for "ViewController.swift".</p>
  
  <p>"ViewController.swift" in <code>Main Editor</code>:</p>
  
  <pre><code>//  ViewController.swift
  //  FoodTracker
  
  import UIKit
  
  class ViewController: UIViewController, UITextFieldDelegate {
      // MARK: Properties
      @IBOutlet weak var nameTextField: UITextField!
      @IBOutlet weak var mealNameLabel: UILabel!
      @IBOutlet weak var mainButton: UIButton!
  
      override func viewDidLoad() {
          super.viewDidLoad()
          nameTextField.delegate = self
      }
  
      // MARK: UITextFieldDelegate
      func textFieldShouldReturn(textField: UITextField) -&gt; Bool {
          textField.resignFirstResponder()
          return true
      }
  
      func textFieldDidEndEditing(textField: UITextField) {
          mealNameLabel.text = textField.text
      }
  
      // MARK: Actions
      @IBAction func setDefaultLabelText(sender: UIButton) {
          mealNameLabel.text = "DEFAULT text"
          // mainButton.tintColor = UIColor.darkTextColor()    
      } 
  }
  </code></pre>
  
  <p>"ViewController.swift" in <code>Assistant Editor</code>:    </p>
  
  <pre><code>//
  //  ViewController.swift
  //  FoodTracker
  import UIKit
  
  internal class ViewController : UIViewController, UITextFieldDelegate {
  
      @IBOutlet weak internal var nameTextField: UITextField!
      @IBOutlet weak internal var mealNameLabel: UILabel!
      @IBOutlet weak var mainButton: UIButton!
  
      override internal func viewDidLoad()
  
      internal func textFieldShouldReturn(textField: UITextField) -&gt; &lt;&lt;error type&gt;&gt;
  
      internal func textFieldDidEndEditing(textField: UITextField) -&gt; &lt;&lt;error type&gt;&gt;
  
      @IBAction internal func setDefaultLabelText(sender: UIButton) -&gt; &lt;&lt;error type&gt;&gt;
  }
  </code></pre>
  
  <p>So, those are completely different different files, but have the same name. The one in the <code>Assistant Editor</code> is the <em>interface</em> while the file shown in the <code>Main Editor</code> is the implementation of the interface, right?</p>
  
  <p>That seems a little weird, but the interface and implementing class have the same name? When I'm working in Xcode I need to be aware that sometimes two files can (often?) have the same name?</p>