Swift segue not working? - ios

Question

My Swift segue is not working at all and isn't throwing any errors. The breakpoint shows me that the app lands on this line but nothing happens:
self.performSegueWithIdentifier("SignupSegue", sender: self)
The code block is a login form with Facebook:
if let accessToken: FBSDKAccessToken = FBSDKAccessToken.currentAccessToken() {
PFFacebookUtils.logInInBackgroundWithAccessToken(result.token, block: {
(user: PFUser ? , error : NSError ? ) - > Void in
if user!.isNew {
self.performSegueWithIdentifier("SignupSegue", sender: self)
} else {
self.navigateToInGame(true)
}
})
}
Here's the segue function it should call, but doesn't even get to it:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?)
{
if (segue.identifier == "SignupSegue") {
let storyboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier("SignUpViewController")
self.showViewController(vc, sender: self)
}
}
Any ideas?

Answer 1

Generally, any UI updating has to be in main thread. I think the block for PFFacebookUtils.logInInBackgroundWithAccessToken is still in the background state in above situation. Maybe trigger the showViewController in dispatch_async(dispatch_get_main_queue(), {}) and see if there is any difference.
dispatch_async(dispatch_get_main_queue(), {
let storyboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier("SignUpViewController")
self.showViewController(vc, sender: self)
})

Answer 2

Ok. I just tried it out. Hope you did all the things regarding StoryBoard Reference.
Me too had the same issue with performSegueWithIdentifier.
Example:
Let take two storyboard main and signup.
1) In main.storyboard create a storyboard reference. Set the storyboardId in the Storyboard Reference as signup and the referencedId as the storyboardId of the scene(viewController) which is in signup.storyboard. Look at this link for a clear picture Storyboard to Storyboard
2) Set the segue identifier between viewController and Storyboard Reference in main.storyboard
3) Since I faced the same problem with performSegueWithIdentifier, I replaced it with shouldPerformSegueWithIdentifier.
override func shouldPerformSegueWithIdentifier(identifier: String, sender: AnyObject?) -> Bool {
if(identifier == "segue_identifier"){
// segue_identifier is the viewController and storyBoard Reference segue identifier.
print("hello")
}
return true;
}
Let me know if you find any issues. It did work for me.

Answer 3

Performing a segue leads to present a new view controller.You don't need to and can't create and show view controller in prepareForSegue.It will look like:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?)
{
if (segue.identifier == "SignupSegue") {
let vc = segue.destinationViewController
}
}

Answer 4

Swift 3 solved:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "SignupSegue") {
DispatchQueue.main.async {
let storyboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewController(withIdentifier: "SignUpViewController")
self.show(vc, sender: self)
}
}
}

Answer 5

You can try this ...
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?)
{
if (segue.identifier == "SignupSegue") {
if let destination = segue.destination as? SignUpViewController {
...
}
}
}

Answer 6

The closest I can get to overcome same problem for myself:
Made trigger var segueLogin : Bool = false with initialised value in the Class.
When PFFacebookUtils gets needed values for segue, change trigger to true:
PFFacebookUtils.logInInBackground(withReadPermissions: permissions) {
(user: PFUser?, error: Error?) -> Void in
if let user = user {
if user.isNew {
print("User signed up and logged in through Facebook!")
self.segueLogin = true
} else {
print("User logged in through Facebook!")
self.segueLogin = true
}
} else {
print("Uh oh. The user cancelled the Facebook login.")
self.loginCancelledLabel.alpha = 1
}
}
Then added code to viewDidAppear class. Realised it starts everytime PFFacebookUtils complete. So it checks if returned value is true and performs segue after successful PFFacebookUtils session:
override func viewDidAppear(_ animated: Bool) {
if segueLogin == true {
self.performSegue(withIdentifier: "segueSingup", sender: self)
}
}