Swift iOS -How to pop to different SegmentControl Index using a NavigationController - ios

Question

//Index=0 //contains buttonToSwitchTab to pop to TabOneVC
TabZeroNavCntrlr ----TabZeroVC --- TabChangeVC
//segmntCntrl /
NavCntlr--ContainerView---
\ //Index=1
TabOneNavCntrlr ---- TabOneVC
I have a NavController that hasContainerView connected to it. Inside the containerView there is a segmentControl. The containerView has 2 more nav controllers connected to it that each lead to their own child controllers: TabZeroVC and TabOneVC. Initially the first view shown is TabZeroVC (selectedSegmentIndex = 0). There is a button inside there that leads to TabChangeVC which has a buttonToSwitchTab inside of it. Pressing that button I want to pop to TabOneVC.
I tried this code below by using my navigation controller to make the switch but on the line tabOneVC.segmentedControl.selectedSegmentIndex = 1 I get a crash: unexpectedly found nil while unwrapping an Optional value
I put a break point on it and the containerVC gets initialized but it's 3 properties segmentedControl, tabZeroVC, and tabOneVC are all coming up as nil. Since segmentedControl is nil that's where the crash is happening.
class TabChangeVC: UIViewController{
#IBAction func buttonToSwitchTab(sender: UIButton){
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let containerVC = mainStoryboard.instantiateViewControllerWithIdentifier("ContainerViewController") as! ContainerViewController
containerVC.segmentedControl.selectedSegmentIndex = 1 //crash happens here
self.navigationController?.popToViewController(containerVC, animated: true)
}
}
ContainerView:
class ContainerViewController: UIViewController{
#IBOutlet weak var segmentedControl: UISegmentedControl!
#IBOutlet weak var tabZeroVC: UIView!
#IBOutlet weak var tabOneVC: UIView!
...
}
TabOneVC is selectedSegmentIndex = 1
My question is how do I pop to TabOneVC from the TabChangeVC and more importantly why is the containerVC's segmentedControl coming up as nil?

Answer 1

let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil
let tabOneVC = mainStoryboard.instantiateViewControllerWithIdentifier("TabOneNavigationController") //TabOneNavCntrlr identifire
tabOneVC.segmentedControl.selectedSegmentIndex = 1
appDelegate.window!.rootViewController = tabOneVC

Answer 2

I don't know why the segmentedControl is coming up as nil but I was able to pop to tabOneVC by using NSNotificationCenter. I created a func named tabSwitch() with the segment I wanted to show and then I added a listener inside the viewDidLoad of the ContainerViewController:
class ContainerViewController: UIViewController{
#IBOutlet weak var segmentedControl: UISegmentedControl!
#IBOutlet weak var tabZeroVC: UIView!
#IBOutlet weak var tabOneVC: UIView!
override func viewDidLoad() {
super.viewDidLoad()
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(tabSwitch), name: "tabSwitch", object: nil)
}
func tabSwitch(){
self.segmentedControl.selectedSegmentIndex = 1
self.tabZeroVC.hidden = true
self.tabOneVC.hidden = false
}
}
Inside the TabChangeVC I added a notifier to trigger it and navigationController?.popToRootViewControllerAnimated(true) to get back to the root vc:
class TabChangeVC: UIViewController{
#IBAction func buttonToSwitchTab(sender: UIButton){
NSNotificationCenter.defaultCenter().postNotificationName("tabSwitch", object: nil)
self.navigationController?.popToRootViewControllerAnimated(true)
}
}