How to stop the Observer in NSNotification to called twice?

Question

I have an observer of NSNotification which is called twice. I do not know what to do with it.

I googled it but no solution found.

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Answer 1

For those looking for a solution in Swift 2.2 and above and who have reached this question like me you can create an extension as follows :

import Foundation

extension NSNotificationCenter {
  func setObserver(observer: AnyObject, selector: Selector, name: String?, object: AnyObject?) {
    NSNotificationCenter.defaultCenter().removeObserver(observer, name: name, object: object)
    NSNotificationCenter.defaultCenter().addObserver(observer, selector: selector, name: name, object: object)
  }
}

You can call this method as follows :

NSNotificationCenter.defaultCenter().setObserver(self, selector: #selector(methodName), name: "name", object: nil)

The extension will handle the removal of previous observer if it exists. Even if there was no previous observer present this code won't crash.