How to segue programmatically in iOS using Swift

Question

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

Solution 1

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)

Solution 2

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.

Solution 3

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)
}

Solution 4

You can use segue like this:

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

    }
}

Solution 5

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)

View more solutions

Comments

[HAS]

Like performSegue:?

[Shlomi Schwartz]

Yes, but the code is not in the viewController, how can I achive this?

[HAS]

Well, in that case you should delegate that work (the segueing) from the object you do the work in to the view controller (via a completion block or a delegate method).

[Chris Hayes]

getting a non nil layout exception

[Shlomi Schwartz]

Thanks for the reply, how can I call performSegueWithIdentifier from a custom class which is not the view?

[Shlomi Schwartz]

Thanks for the reply, however performSegueWithIdentifier is a viewController method, and my code runs in an external class

[iamprem]

If i use your second method. How to pass data to the next view?

[Lloyd Sargent]

You would use func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) and set the properties.

[GajananB]

Note when calling performSequeWithIdentifer(), an implementation of prepareForSeque() in your calling controller will be called and you can do various data passing there - in fact, the sender parameter received in prepareForSeque() is simply what is passed to the sender parameter in performSequeWithIdentifier()

[Chris Hayes]

getting a non nil layout exception

[scaryguy]

What if the segue does not exist in the storyboard? For example, if you want to create a segue to ViewController itself?

[mfaani]

I think after Mohit's edit the answer has became confusing. Assuming that mySegueID is pointing to some viewController inside StoryBoard...it would work with or without having a class in its identity inspector.If it's not pointing to a class then the viewController would be not having any specific functionality other than what you see in the storyboard itself. If you give it a class then it would benefit from what ever functionality the class has inside it. But if you just do presentViewController or pushViewController WITHOUT pointing to any viewController's storyboard ID

[mfaani]

then you won't get anything from storyboard, you would just get what's written in the code. So if you want to have both ie functionality of written code + views & outlets from your storyboard then you must do something like the answer in this link ie you MUST 1) link viewController to class in storyboard 2) use instantiateViewControllerWithIdentifier to be able to get whatever you did in storyboard and (since you already did step 1 you would also have functionality from code) 3) then do your push or present.

[mfaani]

@scaryguy see my comments @@Jerome, I didn't make the edit myself, because I thought it would get rejected because of deviation from original author ... so please edit if you agree

[Michael Samoylov]

Swift 3: NotificationCenter.default.addObserver(self, selector: #selector(goToDifferentView), name: NSNotification.Name(rawValue: "segue"), object: nil)

[Maxim]

@iamprem We can use method optional public func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) of the Navigation Controller you are pushing another UIViewController on. Note the Navigation Controller needs to be a delegate to invoke that method, meaning inside the Navigation Controller's vieDidLoad() we need to write: self.delegate = self.

[etayluz]

What in the world is nextViewController ?? I'm getting unresolved identifier

[Bishan]

Perfect! This fixed my issue! 1+

[Ryan]

If I am using storyboards, is it better practice to create a segue and use performSegueWithIdentifier or just use presentViewController?

[uliwitness]

Please do not abuse notifications like this. Use a delegate and make the connection between the view controller and your class explicit. It is near-impossible to observe the control flow of a notification, because there could be multiple subscribers, and instances can subscribe/unsubscribe at will.

[Rajneesh071]

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