How to segue programmatically in iOS using Swift

I'm creating an app that uses the Facebook SDK to authenticate users. I'm trying to consolidate the facebook logic in a separate class. Here is the code (stripped for simplicity):

import Foundation

class FBManager {
    class func fbSessionStateChane(fbSession:FBSession!, fbSessionState:FBSessionState, error:NSError?){
        //... handling all session states
        FBRequestConnection.startForMeWithCompletionHandler { (conn: FBRequestConnection!, result: AnyObject!, error: NSError!) -> Void in
        
            println("Logged in user: \n\(result)");
        
            let storyboard = UIStoryboard(name: "Main", bundle: NSBundle.mainBundle())
            let loggedInView: UserViewController = storyboard.instantiateViewControllerWithIdentifier("loggedInView") as UserViewController
        
            loggedInView.result = result;
        
            //todo: segue to the next view???
        }
    }
}

I'm using the above class method to check session state changes, and it works fine.

Q: Once I have the user's data, how can I segue to the next view from within this custom class?

Just to be clear, I have a segue with identifier on the storyboard, and I'm trying to find a way to perform a segue from a class which is not the view controller

If your segue exists in the storyboard with a segue identifier between your two views, you can just call it programmatically using:

performSegue(withIdentifier: "mySegueID", sender: nil)

For older versions:

performSegueWithIdentifier("mySegueID", sender: nil)

You could also do:

presentViewController(nextViewController, animated: true, completion: nil)

Or if you are in a Navigation controller:

self.navigationController?.pushViewController(nextViewController, animated: true)

If your segue exists in the storyboard with a segue identifier between your two views, you can just call it programmatically using

self.performSegueWithIdentifier("yourIdentifierInStoryboard", sender: self)

If you are in Navigation controller

let viewController = YourViewController(nibName: "YourViewController", bundle: nil)        
self.navigationController?.pushViewController(viewController, animated: true)

I will recommend you for second approach using navigation controller.

You can use NSNotification

Add a post method in your custom class:

NSNotificationCenter.defaultCenter().postNotificationName("NotificationIdentifier", object: nil)

Add an observer in your ViewController:

NSNotificationCenter.defaultCenter().addObserver(self, selector: "methodOFReceivedNotication:", name:"NotificationIdentifier", object: nil)

Add function in you ViewController:

func methodOFReceivedNotication(notification: NSNotification){
    self.performSegueWithIdentifier("yourIdentifierInStoryboard", sender: self)
}

You can use segue like this:

self.performSegueWithIdentifier("push", sender: self)
override func prepareForSegue(segue: UIStoryboardSegue!, sender: AnyObject!) {
    if segue.identifier == "push" {

    }
}

Swift 3 - Also works with SpriteKit

You can use NSNotification.

Example:

1.) Create a segue in the storyboard and name the identifier "segue"

2.) Create a function in the ViewController you are segueing from.

func goToDifferentView() {

    self.performSegue(withIdentifier: "segue", sender: self)

}

3.) In the ViewDidLoad() of your ViewController you are segueing from create the observer.

NotificationCenter.default.addObserver(self, selector: #selector(goToDifferentView), name: "segue" as NSNotification.Name, object: nil)

Update - Last time I used this I had to change the .addObserver call to the following code to silence the errors.

NotificationCenter.default.addObserver(self, selector: #selector(goToDifferentView), name: NSNotification.Name(rawValue: "segue"), object: nil)

4.) In the ViewController or Scene you are segueing to, add the Post Method wherever you want the segue to be triggered.

NotificationCenter.default.post(name: "segue" as NSNotification.Name, object: nil)

Update - Last time I used this I had to change the .post call to the following code to silence the errors.

NotificationCenter.default.post(NSNotification(name: NSNotification.Name(rawValue: "segue"), object: nil) as Notification)

How to segue programmatically in iOS using Swift

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