Passing Data in Swift

Question

I have been looking for an answer for this, but have only found answers for segues.

I have viewController1 with a button that segues to viewContr

Answer 1

(Swift 2.1, Xcode 7, iOS9) If you don't want it to be tightly coupled only between 2 ViewControllers, You can also use the Notification Design Pattern (Post & Observe), which is mainly used to pass on the same object/information from one VC to multiple View Controllers.

For your scenario : In VC2.swift :

@IBAction func BackBtn(sender: UIButton) {  
  NSNotificationCenter.defaultCenter().postNotificationName("ThisIsTheMessage", object: nil, userInfo:["ObjectBeingSent":yourObject])

}

And in VC1.swift :

override func viewDidLoad() {
        super.viewDidLoad()
        NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("yourFunction:"), name: "ThisIsTheMessage", object: nil)
    }



func yourFunction(theNotification : NSNotification) {

           if let extractInfo = theNotification.userInfo {
     //code to use the object sent from VC2, by extracting the object details
    }
     }

Common Practise is:

1. Pass data forward -> Use PrepareForSegue
2. Pass data backward to the previous View Controller-> Protocol and Delegation
3. Pass data across multiple View Controllers -> Notifications : Post and Observe(observe in all the View controllers where you are using the object details)