title: How to change the title of the "back" bar button item?
body: <p>I want to change the "Root View Controller" back button to "Back" without changing the title of the Root View Controller.</p>
  
  <p>I have tried these 3 code but all of them do not work.</p>
  
  <pre><code>navigationItem.backBarButtonItem?.title = "Back"
  navigationItem.leftBarButtonItem?.title = "Back"
  navigationItem.backBarButtonItem?.title = "Back"
  </code></pre>
  
  <p>May I know what am I doing wrong?
  Thanks in advance.</p>
  
  <p><a href="https://i.stack.imgur.com/DQBBx.png" rel="noreferrer"><img src="https://i.stack.imgur.com/DQBBx.png" alt="Screenshot"></a></p>
  
  <p>Here is the code of the whole method for your reference:</p>
  
  <pre><code>override func viewDidLoad() {
      super.viewDidLoad()
      // Do any additional setup after loading the view, typically from a nib.
  
      navigationItem.backBarButtonItem?.title = "Back"
      navigationItem.leftBarButtonItem?.title = "Back"
  
      manager = CLLocationManager()
      manager.delegate = self
      manager.desiredAccuracy = kCLLocationAccuracyBest
  
      if activePlace == -1
      {
          manager.requestWhenInUseAuthorization()
          manager.startUpdatingLocation()
      }
      else
      {
         // print( "String(myvar3.dynamicType) -&gt; \(places[activePlace]["lat"].dynamicType)")
          let latitude = Double(places[activePlace]["lat"]!)
          let longitude = Double(places[activePlace]["lon"]!)
  
          //creating map region and annotation
          createMapRegionAndAnnotation(latitude!, longitude: longitude!)
  
          print(latitude)
      }
  </code></pre>