How to safely removeObserver (Swift) - ios

Question

I have added an observer
override func viewDidLoad()
{
super.viewDidLoad()
NSNotificationCenter.defaultCenter().addObserver(self, selector:"selector name", name: "observer name", object:nil)
...
}
When removing observer in deinit,
deinit
{
NSNotificationCenter.defaultCenter().removeObserver(self, forKeyPath: <some string>)
}
the app sometimes crashes:
Terminating app due to uncaught exception 'NSRangeException', reason:
'Cannot remove an observer "class"
for the key path "some string" from
NSNotificationCenter because it is not registered as an
observer.
So I am trying to add do/catch
deinit
{
do{
try NSNotificationCenter.defaultCenter().removeObserver(self, forKeyPath: <some string>)
}catch{}
}
But I get a warning:
catch block is unreachable because no errors are thrown in do block
And the app crashes
and when I am adding a try
deinit
{
do{
try NSNotificationCenter.defaultCenter().removeObserver(self, forKeyPath: <some string>)
}catch{}
}
I get this warning:
no calls to throwing functions occur within try expresion
And the app crashes
How should that be done?

Answer 1

If you support iOS Versions by 9.0 you don't need to remove observers by yourself in your deinit method.
Taken from the documentation
In OS X 10.11 and iOS 9.0 NSNotificationCenter and
NSDistributedNotificationCenter will no longer send notifications to
registered observers that may be deallocated.
https://useyourloaf.com/blog/unregistering-nsnotificationcenter-observers-in-ios-9/

Answer 2

I think you should use code
NSNotificationCenter.defaultCenter().removeObserver(self)
Explain:
You have mistake here: You are using NSNotification & NSNotificationCenter so you have to using this code above to remove observe.
you have use code for KVO to remove observer so it will wrong.
More detail you can read at here. Key-Value-Observing