How to identify the segue identifier on destination view controller? - ios

Question

I have two view controllers, the first one has two buttons, signup and login, the second VC does the function of signup and login stuff (I wrote functions to switch between signup and login mode), is it possible to identify if user pressed login/signup button in the first VC so the right function will be called in the second VC when performing segue?

Answer 1

You have tell the second view controller what to do upon the first view controller selected option (signin or signup). I would assume that you could do this by simply declaring a flag and send it to the second view controller, for instance:
Declare a boolean variable in your second view controller (let's say shouldBehavesAsLogin) which means if selection is login it should be true:
// Controller that could represents signin or signup:
class SecondViewController: UIViewController {
//...
var shouldBehavesAsLogin = false
// ...
}
thus you could determine what is the value that should be assigned to it based on which button tapped, first view controller:
class FirstViewController: UIViewController {
// ...
private var isLoginTapped = false
#IBAction func signinTapped(sender: UIButton) {
isLoginTapped = true
}
#IBAction func signupTapped(sender: UIButton) {
// nothing to do here, isLoginTapped is false by default...
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "MySegue"{
if let nextViewController = segue.destination as? SecondViewController {
nextViewController.shouldBehavesAsLogin = isLoginTapped
}
}
}
// ...
}
Thus all you have to do is to check the value of shouldBehavesAsLogin whether is it true to let the controller behaves as login or false to do the opposite.
Additional Tip:
If the purpose of adding IBActions for each button is just navigating to the second view controller, I would suggest to let both of the buttons to have the same IBAction, but you should let the sender to be of type UIButton instead of Any, thus you could do -for instance-:
#IBAction func aButtonTapped(sender: UIButton) {
// do the default behvior for both signin and signup (navigate to the second controller)
// signinButton is the button you tap for navigating to second controller to behaves as signin
isLoginTapped = sender === signinButton ? true : false
}

Answer 2

This answer assumes there is only one segue between the two view controllers. If there is more than one, you can simply use the segue identifier in prepareForSegue.
I'd handle this by using the sender parameter on either -prepare(for segue:sender:) or -performSegue(withIdentifier:sender), depending on whether you are triggering the segue directly from the button or in code.
If the buttons are triggering the segue, you can test whether the sender params is one of the two buttons concerned, and perform appropriate setup on the destination VC. If the segue is being triggered in code in an IBAction method, you could either pass through the button reference from the IBActions sender parameter, or pass some other identifying object that your prepareForSegue method is able to deal with.
Bear in mind that the target VC's views will not have loaded when prepareForSegue is called, so you may need to set some state on the target VC (e.g. a login/signup enum property) which is then used to set up the VC appropriately when its -viewDidLoad is called.