How to update a variables/UI in a view that was initialized from a separate file?

It is a bit difficult to understand all the explanation, but I hope I catched the essence.

First point: you should not think in term of files but in term of objects. The question is not if a var is declared in a file but if it is declared in a class.

So the question is how to communicate between classes, without creating references of all var in all objects.

I'll handle the case where you want to modify a property (var) propertyInA in class A from a call in class B

You have several mechanisms.

You have several ways to achieve this:

- send notification

- use delegation

- directly set the property : vc1.property = ...., called from vc2 // not very clean design

1. You can use notifications:

you declare, outside classes, the name of notification

let notification1Name = "notification1"       // select an appropritae name for the constant to ease further reading, better than notification1 and notification1Name

- In class A (in the viewDidload for instance), you subscribe to a notification by creating an observer:

       NotificationCenter.default.addObserver(self, selector: #selector(notification1Action), name:NSNotification.Name(rawValue: notification1Name), object: nil) // object is nil: we don't test you sent the notification ; but we could give an object reference if we wanted to test

- in class A, you define the func that will update the var ou outlets you want to modify

func notification1Action()  {
     propertyInA = //
     // Can be a textField content as well
     textFieldInA.text = "I updated"
}

- in class B, you post the notification when you want to update properties of class A

        let nc = NotificationCenter.default
        nc.post(name: Notification.Name(rawValue: notification1Name), object: self)

2. You can use delegation where class B will delegate to class A the update

So if I have 50 classes/views that use the same "textField" class. I will need to have the function "notification1Action()" in all 50 classes? I understand the usage of notifications/delegate (and prefer delegates), but I was trying to avoid repeating the same function in every view.

Do you have 50 different classes or 50 instances of object of the same class ?

If they are 50 instances of the same class, (that is what I understand) you will have the code once.

However, if they are of different class, you have to replicate in each class… unless you decide to create an intemediate subclass where you implement the function and have all 50 classes inherent from this intermediate class.

Here is the structure

class ViewForDelegation : UIView {

// In a didLoad method


     NotificationCenter.default.addObserver(self, selector: #selector(notification1Action), name:NSNotification.Name(rawValue: notification1Name), object: nil) // object is nil: we don't test you sent the notification ; but we could give an object reference if we wanted to test

     func notification1Action()  {
          propertyInA = //
          // Can be a textField content as well
          textFieldInA.text = "I updated"
     }
}

// Then the 50 classes
class ViewNumber1 : ViewForDelegation {

}

Yes they are different classes. For example, HomeMenu/Chat Room/Game Start/Game/Game Finished/Game Leaderboards... all of these will need to load a "Game Header" view that will display username & gold amount (as an example) and will need to be updated with the correct gold amount (if it changes).