Swift, protocol and variable values not stored...? - ios

Question

I'm new to protocols and pageview controllers and I tried to something I hoped was simple. To pass a variable value from the content viewcontroller to the page list viewcontroller but it doesn't work so I'm doing something wrong...
In my storyboard I have a ViewController (as the Page List viewcontroller) and embedded in a navigation controller. The navigation bar has a button on it.
There is a PageContentViewController that has a label.
The code I use follows (EDITED with the accepted solution provided by #Tom Elliott):
protocol setRoomOnScreenProtocol {
func updateRoomOnScreen(myRoom: String)
}
class ViewController: UIViewController, UIPageViewControllerDataSource, UIPageViewControllerDelegate, setRoomOnScreenProtocol {
#IBAction func press1(sender: AnyObject) {
println("roomOnScreen: \(roomOnScreen)")
println("pageTitles: \(pageTitles)")
}
#IBOutlet weak var btn1: UIBarButtonItem!
let pageTitles = ["Room 1", "Room 2", "Room 3", "Room 4"]
var count = 0
var pageViewController : UIPageViewController!
var roomOnScreen: String = ""
override func viewDidLoad() {
super.viewDidLoad()
reset()
}
func updateRoomOnScreen(myRoom: String) {
roomOnScreen = myRoom
println("roomOnScreen (PGL): \(roomOnScreen)")
}
func reset() {
/* Getting the page View controller */
pageViewController = self.storyboard?.instantiateViewControllerWithIdentifier("PageViewController") as! UIPageViewController
self.pageViewController.dataSource = self
let pageContentViewController = self.viewControllerAtIndex(0)
self.pageViewController.setViewControllers([pageContentViewController!], direction: UIPageViewControllerNavigationDirection.Forward, animated: true, completion: nil)
self.pageViewController.view.frame = CGRectMake(0, 0, self.view.frame.width, self.view.frame.height)
self.addChildViewController(pageViewController)
self.view.addSubview(pageViewController.view)
self.pageViewController.didMoveToParentViewController(self)
}
func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
var index = (viewController as! PageContentViewController).pageIndex!
index++
return self.viewControllerAtIndex(index)
}
func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
var index = (viewController as! PageContentViewController).pageIndex!
if (index <= 0) {
return nil
}
index--
return self.viewControllerAtIndex(index)
}
func viewControllerAtIndex(index : Int) -> UIViewController? {
if ((self.pageTitles.count == 0) || (index >= self.pageTitles.count)) {
return nil
}
let pageContentViewController = self.storyboard?.instantiateViewControllerWithIdentifier("PageContentViewController") as! PageContentViewController
pageContentViewController.delegate = self
pageContentViewController.titleText = self.pageTitles[index]
pageContentViewController.pageIndex = index
return pageContentViewController
}
func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
return pageTitles.count
}
func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
return 0
}
}
and the PageContentViewController:
class PageContentViewController: UIViewController {
var pageIndex: Int?
var titleText : String!
var delegate: setRoomOnScreenProtocol!
#IBOutlet weak var label1: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
self.label1.text = self.titleText
}
override func viewDidAppear(animated: Bool) {
if let actualDelegate = self.delegate {
actualDelegate.updateRoomOnScreen(titleText)
} else {
println("error")
}
doMore()
}
func doMore() {
println("showing...:\(titleText)")
}
}
When I move through the pages I correctly get the output:
roomOnScreen (PGL): Room 1
showing...:Room 1
roomOnScreen (PGL): Room 2
showing...:Room 2
But when I hit the navigation bar button I get no value...
roomOnScreen:
pageTitles: [Room 1, Room 2, Room 3, Room 4]
What am I doing wrong...?
Thanks!

Answer 1

The line:
self.delegate = ViewController()
Is actually creating a brand new instance of ViewController each time it is called, so the original ViewController that is visible is not receiving the message.
I'd suggest setting the delegate when you initially create the pages:
let pageContentViewController = self.storyboard?.instantiateViewControllerWithIdentifier("PageContentViewController") as! PageContentViewController
pageContentViewController.delegate = self