NSNotificationCenter one post causes observers to be called twice

This is possible when your code for addObserver is executed twice. The notification function will be called as many times as it is registered.

So make sure your code for adding observer is executed for once only. So, you can keep it in viewDidLoad or init method.

If you are putting it in viewWillAppear then remove observer in viewWillDisAppear.

before you add observer, make sure you remove the previous observer added.

[[NSNotificationCenter defaultCenter]removeObserver:self];[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(newsfeedFetchCompleted:) name:kNewsfeedFetchCompleted object:nil];

It is possible if you have added the same observer multiple times for the newsfeedFetchCompleted notification. You should match your addObserver calls with removeObserver calls.

For example if you added the observer in viewWillAppear/viewWillDidAppear/ViewDidLoad of a UIViewController, you should remove it in viewWillDisappear/viewDidDisappear/ViewDidUnload.

The corresponding remove call for addObserver, is removeObserver:name:object:

More info can be found in the NSNotificationCenter docs