Does removeObserver() remove all observers?

swift nsnotificationcenter
4thSpace picture 4thSpace · Apr 21, 2015 · Viewed 19.7k times · Source

Does the following remove all NSNotificationCenter.defaultCenter there were added by name a view?

NotificationCenter.default.removeObserver(self)

If I have the following in the same view of viewDidLoad(), will they be removed with the single line above?

NotificationCenter.default.addObserver(self, selector: Selector(("method1")), name: UITextField.textDidChangeNotification, object: nil)

NotificationCenter.default.addObserver(self, selector: Selector(("method2")), name: UITextView.textDidChangeNotification, object: nil)

Answer

Duncan C picture Duncan C · Apr 21, 2015

Yes, the removeObserver(self) call will remove all observers that you added using addObserver:selector:name:object: with an observer of self, regardless of the notification name, object, or selector you specified.

It is a bad idea to use the removeObserver(self) method anywhere but in your object's deinit method, because some system classes (or subclasses of objects that you define) may have added observers that you don't know about. That method call is a "scorched earth" call the removes ALL observers from the object.

Instead you should call removeObserver:name:object: and remove only the observers that you added.

Related questions

NSNotificationCenter addObserver in Swift

How do you add an observer in Swift to the default notification center? I'm trying to port this line of code that sends a notification when the battery level changes. [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(batteryLevelChanged:) name:UIDeviceBatteryLevelDidChangeNotification object:…

Read More
Move view with keyboard using Swift

I have an app that has a text field on the lower half of the view. This means that when I go to type in the text field the keyboard covers the textfield. How would I go about moving the …

Read More
How to pass data using NotificationCenter in swift 3.0 and NSNotificationCenter in swift 2.0?

I'm implementing socket.io in my swift ios app. Currently on several panels I'm listening to the server and wait for incoming messages. I'm doing so by calling the getChatMessage function in each panel: func getChatMessage(){ SocketIOManager.sharedInstance.getChatMessage { (messageInfo) …

Read More