Conditional Segue in Swift

Question

I want to do a \"connexion\" button in my app. And when you tap on it, it will open a new page if you have correct login.

But, I read that we can\'t undo a segue, I

Answer 1

You can do the credentials check in the following method in your ViewController:

func shouldPerformSegueWithIdentifier(_ identifier: String!,
                              sender: AnyObject!) -> Bool

In alternative, you can bind the UIButton to an action in your view controller, perform the checks here and then trigger a segue by code.

Answer 2

In Swift you can proceed by:

Step 1: Insert a segue from ViewControllerA to ViewControllerB. The segue should start from ViewControllerA itself and not from any control (like Button).

Step 2: Give segue an unique identifier in storyboard. Ex: seageFromAtoB

Step 3 : In your ViewControllerforA.swift write :

if(condition == true) {
    self.performSegueWithIdentifier("seageFromAtoB", sender: self)
}

If you are performing some task in some other Thread then using performSegueWithIdentifier can throw an exception.

If you get this error then you should use :

if(condition==true){
      NSOperationQueue.mainQueue().addOperationWithBlock {
           self.performSegueWithIdentifier("seageFromAtoB", sender: self)
      }
}

This will perform segue from ViewControllerA to ViewControllerB with a specific condition.