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Questions tagged [nsnotification]

NSNotification is a class used to send messages to observing classes through NSNotificationCenter.

NSNotification is a class used to send messages to observing classes through NSNotificationCenter. Notifications must have a name and can be optionally associated with a specific object. If an object is provided, the notification is only delivered to a class that is also observing the exact same name and object.

To send a notification, use NSNotificationCenter's postNotification: (a convenience function postNotificationName:object:userInfo: also exists which creates a notification and posts it with a single call). Classes posting a notification can also include an optional userInfo parameter to pass an object to the receiving class.

For more information, see Apple's documentation for NSNotification and NSNotificationCenter.

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NSNotification to detect other program's crashes

I was planning on writing a small daemon that detected whether another app crashed, thinking all the while that the system would send an NSWorkspaceDidTerminateApplicationNotification, but this is not the case. Assuming that I do not want to create…
Andrew J. Freyer
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addobserver / removeobserver query

Is it OK to use -removeObserver: first and then call -addObserver: with the same name? Or is it a rule to have -addObserver: first before -removeObserver:? I tried it using OS 4.0 and it seems OK (no crash, warnings... etc.). -(void)…
mark
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How to create a class to send and receive events through NSNotificationCenter in Objective-C?

I need to create two classes and both should be able to send and receive the events through the NSNotificationCenter methods.ie Both should have the sendEvent and receiveEvent methods: @implementation Class A -(void)sendEvent { …
Cathy
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Is there a way to check if observer listens to some NSNotification?

I want to check if my view is listening for UIApplicationWillResignActiveNotification or not. If it is listening then I want to remove it during dealloc. Now I was wondering if there is way to do this using objective c ? I am not trying avoid…
slonkar
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Logging NSNotifications

I would like to log any NSNotifications posted by a single NSNotificationCenter shared accross my application. I have tried subclassing NSNotificationCenter with the intention of adding logging code to the three post methods, but it returns an…
Undistraction
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Should I unregister NSNotification both in viewDidUnload and dealloc?

I register a NSNotification in viewDidLoad method. Should I unregister it both in viewDidUnload and dealloc method using the code below? [[NSNotificationCenter defaultCenter] removeObserver:self]; Thanks.
tangqiaoboy
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How to migrate NSWorkspace notifications to Swift 4?

In Swift 3 I registered for sleep and wake notifications with this code: let notificationCenter = NSWorkspace.shared.notificationCenter notificationCenter.addObserver(self, selector: #selector(AppDelegate.sleepListener), name:…
Daniel Compton
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Value for UIKeyboardAnimationDurationUserInfoKey is zero when QuickType bar shows/hides. Why?

I use the UIKeyboardWillChangeFrameNotification for changing my views when the keyboard is shown. To animate along with the keyboard, I use the NSNotification's user info dictionary to get the duration of the animation, with the…
ArVID220u
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AVPlayerItemDidPlayToEndTimeNotification not being called with iOS 8

AVPlayerItem *currentItem = self.player.currentItem; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playerItemDidReachEnd:) name:AVPlayerItemDidPlayToEndTimeNotification object:currentItem]; I have the above notification…
rcat24
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Forcing a language change notification iOS

my app is being localized and we are concerned with dialects. (ie. difference between spanish and spanish in peurto rico) I notice that just changing the region doesn't push a notification to the app that will trigger the localization.. only…
erik
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Sending data between VCs using NSNotificationCenter

I need to pass a NSMutableDictionary from one class (ViewControllerA) to another (ViewControllerB) using NSNotificationCenter. I have tried the following code but it doesn't work. I actually pass to the ViewControllerB but the -receiveData method…
IOS_DEV
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NSNotification troubles

When my class initializes, it adds itself as an observer for a bunch of different Wi-Fi notifications. For some reason, the selector isn't running when any of these things happen. Any ideas? Thank you ahead of time. -(id) init { if (self) { …
Tanner Silva
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Creating No Empty Selections in NSCollectionView

I have set up an NSCollectionView in a cocoa application. I have subclassed the collection view's NSCollectionViewItem to send me a custom NSNotification when one of its views it selected / deselected. I register to receive a notification within my…
GravityScore
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Giving notification to another class with NSNotificationCenter

So my goal is to deliver a notification to another class with using NSNotificationCenter, I also want to pass object with the notification to the other class, how should I do this?
Samuli Lehtonen
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Obj-C Cocoa Notification NSApplicationDidResignActiveNotification

I've a class called AppController.h/m I want to make something when the NSNotificationDidResignActiveNotification is sent. So i wrote this code in AppController.m: -(void) initialize(){ [[NSNotificationCenter defaultCenter] addObserver:self …
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