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I am trying to maintain a login record for a user in swift IOS application. I have a Login view controller in which after successfully logging in the user, i am posting a notification. 

let infodict =  ["userLoggedIn": true]
NotificationCenter.default.post(name: 
NSNotification.Name(rawValue:"NotificationuserLoggedIn"), object: nil, userInfo: infodict)

And in viewdidload of my Home view controller, i am adding observer to it like

NotificationCenter.default.addObserver(self, selector: 
#selector(self.toggleLoginButtonText(_:)), name: 
NSNotification.Name(rawValue:"NotificationUserLoggedIn"), object: nil)

The observer will call the function "toggleLoginButtonText". And in this function i am toggling the text of a login button. If user is logged in the button text should be "Log out" and "Log In" otherwise. Everything works fine till now.

The problem: I want that whenever the user logs out by pressing the button, i update the user info of the the same notification. And then i viewwillappear function of my home controller, i will call "toggleLoginButtonText" function and it will check for notification value. if value of "userLoggedIn" (because user logged out), my function will change the text of login button.

So summing up, My question is two fold.

  1. How to update my notification's userinfo when user logs in and logs out

  2. Is this a good way of handling user logged in record, or there are better ways than this?

    I have one more idea in my mind. "when user logs out, post another notification and observer it in my home controller, and when user logs in again, post another notifiaction, so on and so forth". but i seems a repetitive task to me.

I have looked for answers to these questions. But there are only answers for how to pass data using notifications which i have already passed.

How to pass data using NotificationCentre in swift 3.0 and NSNotificationCenter in swift 2.0?

How to pass data using NotificationCentre in swift 3.0 and NSNotificationCenter in swift 2.0?

Rahul Kumar
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Awais Fayyaz
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2 Answers2

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Not sure if I understand you correctly, but of course you can pass a different dictionary each time with your notification. Instead of let infodict = ["userLoggedIn": true], do let infodict = ["userLoggedIn": isUserLoggedIn], where isUserLoggedIn is your Bool variable of login state.

But in general I'd suggest you to have a shared instance, something like LoginManager which would hold and update your login state, and could be accessed by all view controllers. So in your view controllers you could check something like this:

if LoginManager.shared.isUserLoggedIn {
    // do something
}

You could combine this with notifications, which in general are more useful for evens rather than states. For instance, use a notification for evens such as userDidLogin and userDidLogout.

Au Ris
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The better solution is to use UserDefaults. Store a boolean in UserDefaults on the key "isLoggedIn" and set it to 'true' when user logs in and 'false' on Logout. In viewWillappear function of home VC, read the value(a boolean) of UserDefaults on key "isLoggedIn" and change whatever you want to.

Zahid Usman Cheema
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