using presentviewcontroller inside a function swift - ios

Question

I am trying to use this inside my function to present a view controller after a function runs, so included it inside
let window = UIWindow()
let rootViewController = window.rootViewController
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: NSBundle.mainBundle())
let setViewController = mainStoryboard.instantiateViewControllerWithIdentifier("EmployeeTBCIdentifier")
rootViewController?.presentViewController(setViewController, animated: true, completion: nil)
It's not doing anything, it works if I use it inside viewDidLoad()
here's the main idea, and would it be possible to use completions according to this example,
func logInType(completion(Void1, Void2)->()) {
if login == employer{
void1
}else if login == employee{
void2
}
}
when using the function I want to return this
func logInType{(void1, void2) -> void in
void1 = self.presentview //I want to push view to another if this code executed
void2 = self.presentview //same idea
}
updated : code is working but it's not pushing to the viewcontroller identified.
dispatch_async(dispatch_get_main_queue()){
let window = UIWindow()
let rootViewController = window.rootViewController
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: NSBundle.mainBundle())
let setViewController = mainStoryboard.instantiateViewControllerWithIdentifier("EmployeeTBCIdentifier")
rootViewController?.presentViewController(setViewController, animated: true, completion: nil)
}

Answer 1

Seems to me that there might be a problem in how you are getting the rootViewController. I think the let window = UIWindow() call is going to return a new UIWindow object instead of what you want which is the window that the root view controller (and your app) is associated with. Continuing this, rootViewController will be nil and your optional chain call rootViewController?.presentViewController(setViewController, animated: true, completion: nil) won't do anything. Use an explicit unwrap via rootViewController!.presentViewController(setViewController, animated: true, completion: nil) and you should see the error
To rectify, get the correct UIWindow another way, either from the UIAppDelegate or from another view controller using OtherViewController.view!.window!

Answer 2

Try using it like so:
dispatch_async(dispatch_get_main_queue())
{
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier("mainView") as! MainViewController
self.presentViewController(vc, animated: true, completion: nil)
}