无法生产＆＃34;＆lt;回到＆＃34;在Swift导航栏上以编程方式

Question

首先让我先说我正在以编程方式完成所有编码。我的问题是我无法制作经典的iOS＆＃34;＆lt; back＆＃34;在我的导航栏中。我怀疑这是因为我没有使用故事板？

这是我用来创建导航栏的功能：

// Makes a navigation Bar
func makeNavigationBar(navigationBar: UINavigationBar, barTitle: String, forwardButton: Bool, backButton: Bool, page: UIViewController){
  // Create a navigation item with a title
  let navigationItem = UINavigationItem()
  navigationItem.title = barTitle

  // Create left navigation item
  if(backButton){
    let leftButton =  UIBarButtonItem(title: "Back", style:   UIBarButtonItemStyle.Plain, target: page, action: "backClicked:")
    // Create two buttons for the navigation item
    navigationItem.leftBarButtonItem = leftButton
  }
  if(forwardButton){
    let rightButton =  UIBarButtonItem(title: "Next", style:   UIBarButtonItemStyle.Plain, target: page, action: "nextClickedClicked:")
    // Create two buttons for the navigation item
    navigationItem.rightBarButtonItem = rightButton
  }
  // Assign the navigation item to the navigation bar
  navigationBar.items = [navigationItem]
  //Adds the bar to the view
  page.view.addSubview(navigationBar)
}

这是我对该功能的电话：

let navigationBar = UINavigationBar(frame: CGRectMake(0, 0, self.view.frame.size.width, height/12)) 
creationFunctions.makeNavigationBar(navigationBar, barTitle: "", forwardButton: false, backButton: true, page: self)

这是＆＃34; backClicked＆＃34;功能：

func backClicked (sender: UIBarButtonItem!){
    self.dismissViewControllerAnimated(true, completion: {});
}

感谢您的帮助。