Swift NotificationCenter remove observer quickest way

Question

I am adding a number of observers in my viewController -- applicationWillResignActive, applicationDidEnterBackground, and many others. I w

Answer 1

Yes

NotificationCenter.default.removeObserver(self)

this line is sufficient to remove the vc observation as long as all are added with

NotificationCenter.default.addObserver

Answer 2

So I'm working with this in an app right now and the answer might not be as straightforward.

In the documentation, it does state that for iOS 9 and above you are no longer required to explicitly remove the observer in the deinit/dealloc methods for objects. https://developer.apple.com/documentation/foundation/notificationcenter/1413994-removeobserver

However, it appears that this is only true for selector based notification observers. I'll be referencing this blog post: https://oleb.net/blog/2018/01/notificationcenter-removeobserver/.

If you are using block based observers you must still manually remove the observers.

addObserver(forName:object:queue:using:) 

The best general way to do this is to capture the tokens in an array, append them when you add the observer and use them for removal when you deinit/dealloc or otherwise need to remove observer behavior for your object.

in your VC/object properties create an array to store observer 'tokens'

var notifObservers = [NSObjectProtocol]()

Register for a block based notification by capturing the function return object and storing it as a token

let observer = NotificationCenter.default.addObserver(forName: , object: , queue:) { [weak self] notification in
    // do a thing here
}
notifObservers.append(observer)

Removal

for observer in notifObservers {
    NotificationCenter.default.removeObserver(observer)
}
notifObservers.removeAll()

Answer 3

@Sh_Khan is right:

NotificationCenter.default.removeObserver(self)

You can get even further, as mentioned in the Apple Documentation:

If your app targets iOS 9.0 and later or macOS 10.11 and later, you don't need to unregister an observer in its dealloc method.