whose view is not in the windows heirarchy - mvvm

Question

I know this question has been asked before but none of the answers in the other questions worked for me. Here is my code:
```
var values = [String: AnyObject]()
func loginUserToFirebase(_ completion: () -> Void) {
let accessToken = FBSDKAccessToken.current()
guard let accessTokenString = accessToken?.tokenString else {fatalError()}
let credentials = FIRFacebookAuthProvider.credential(withAccessToken: accessTokenString)
FIRAuth.auth()?.signIn(with: credentials, completion: { (user, error) in
if error != nil {
print(error ?? "Something went wrong")
return
}
self.fbGraphRequest()
})
}
internal func fbGraphRequest(){
FBSDKGraphRequest(graphPath: "/me", parameters: ["fields": "id, name, email"]).start { (connection, result, error) in
if error != nil {
print(error ?? "error unknown")
return
} else {
print(result ?? "no result")
self.values = result as! [String: AnyObject]
print(self.values)
weak var rootViewModel = RootViewModel()
rootViewModel?.values = self.values
self.presentRootViewController()
}
}
}
internal func presentRootViewController() {
let loginController = LoginController()
let rootViewController = RootViewController()
loginController.present(rootViewController, animated: true,
completion: nil)
}
```
and here is my error:
Attempt to present <Art_Cache.RootViewController: 0x7fa6a1c2aab0> on <Art_Cache.LoginController: 0x7fa6a1c840b0> whose view is not in the window hierarchy!
This snippet worked when I had this in my LoginViewController and I used self.present(rootViewController, animation: true, completion: nil). Im trying to convert my project to MVVM and this is what's happening. The problem seems to be around the self.presentRootViewController(). These functions are fired upon pressing the facebook login button. Please help and cheers!

Answer 1

This happens when you current view controller's is not the part of window, could you change
func topViewController(_ base: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
if let nav = base as? UINavigationController {
return topViewController(nav.visibleViewController)
}
if let tab = base as? UITabBarController {
let moreNavigationController = tab.moreNavigationController
if let top = moreNavigationController.topViewController, top.view.window != nil {
return topViewController(top)
} else if let selected = tab.selectedViewController {
return topViewController(selected)
}
}
if let presented = base?.presentedViewController {
return topViewController(presented)
}
return base
}
topViewController()?.present(rootViewController, animated: true,
completion: nil)