Swipe Page View Controller and update page number - ios

Question

I have a UIPageViewController in my program. I have added a UITextView programmatically at the top of UIPageViewController.I want to update the text of UITextView with each swipe to page 1 of n or 2 of n or ….
How should I update the TextView to have the correct image number? Where should I call updateStatusLabelText function?
The reason why I used UITextView is that I could not add a UILabel with constraints through code to the top of UIPageViewController.
First class is as follows:
class MainPageViewController: UIPageViewController {
let dS = MainPageViewControllerDataSource()
var statusText : String = ""
var statusTextView = UITextView()
override func viewDidLoad() {
super.viewDidLoad()
statusTextView = UITextView(frame: view.bounds)
statusTextView.text = statusText
statusTextView.editable = false
statusTextView.textAlignment = .Center
statusTextView.font = UIFont(name: statusTextView.font!.fontName, size: 18)
statusTextView.textColor = UIColor.blackColor()
view.backgroundColor = UIColor.whiteColor()
view.addSubview(statusTextView)
view.sendSubviewToBack(statusTextView)
}
func updateStatusLabelText(arrayKey:Int){
statusTextView.text = "\(arrayKey + 1) of \(imageArray.count) "
}
override func viewWillAppear(animated: Bool) {
dataSource = dS
setViewControllers([dS.viewControllerAtIndex(0) as TutorialViewController], direction: .Forward, animated: true, completion: nil)
}
}
Second class
class MainPageViewControllerDataSource: NSObject, UIPageViewControllerDataSource,UIPageViewControllerDelegate {
var tutorialViewControllerDelegate: TutorialViewControllerDelegate?
var pageIndex = Int()
func viewControllerAtIndex(index: Int) -> TutorialViewController {
let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier("tutorialVC") as! TutorialViewController
vc.myImage = imageArray[index]
vc.pageIndex = index
self.pageIndex = index
return vc
}
func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
var index = (viewController as! TutorialViewController).pageIndex
index -= 1
switch index {
case Int.min ... (-1):
return nil
case NSNotFound:
fatalError("NSNotFound. Should crash.")
case imageArray.count..<Int.max:
return nil
default:
return viewControllerAtIndex(index)
}
}
func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
var index = (viewController as! TutorialViewController).pageIndex
index += 1
switch index {
case Int.min ... (-1):
return nil
case NSNotFound:
fatalError("NSNotFound. Should crash.")
case imageArray.count ..< Int.max:
return nil
default:
return viewControllerAtIndex(index)
}
}
func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
return imageArray.count
}
func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
return pageIndex - 1
}
}
Third class:
class TutorialViewController: UIViewController, UIPageViewControllerDelegate {
#IBOutlet weak var imageToPresent: UIImageView!
var itemIndex: Int = 0
var myImage : MyImage?
var pageIndex = Int()
override func viewDidLoad() {
super.viewDidLoad()
imageToPresent = myImage
}
}