nsnotificationcenter

In one of my view controller, it adds itself as observer of UITextViewTextDidEndEditingNotification notification, like the following does [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(done:) name:UITextViewTextDidEndEditingNotification object:nil]; Now I am wondering - do I need to do the following when the view controller is dealloc'd [[NSNotificationCenter defaultCenter] removeObserver:self]; yes, you should always remove any observers when they're being dealloc'd. otherwise the notification center will keep references to the now-dealloc'd objects around and

I'm developing a Cocoa application that shows a list of opened windows and highlights the current focused one. My problem is that I can't find a system notification to inform my app that the main (aka "focused" or "foreground") window has changed. I tried with: [[[NSWorkspace sharedWorkspace] notificationCenter] addObserver:self selector:@selector(wsNotificationHook:) name:NSWorkspaceDidActivateApplicationNotification object:nil]; but it monitors APPLICATION change: it isn't get fired when a change of window is executed INSIDE the same application (for example, if I pass between two Firefox

I'm trying to keep a text field sitting atop the keyboard in iOS 8. But when a user swipes up or down the top of the keyboard to show or dismiss iOS 8 word suggestions, I need to a notification of the new height of the keyboard so I can move my text field up or down by that height. How can I accomplish this? Thanks! You can register for UIKeyboardDidShowNotification and then get the keyboard frame from the notification with UIKeyboardFrameEndUserInfoKey. [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleKeyboardDidShowNotification:) name

I have a class that manages messages coming from and going to an external accessory to an iPad. In the init I have the following code: - (id) init { self = [super init]; if (!self) return; [[EAAccessoryManager sharedAccessoryManager] registerForLocalNotifications]; //we want to hear about accessories connecting and disconnecting [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(accessoryDidConnect:) name:EAAccessoryDidConnectNotification object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(accessoryDidDisconnect:) name

When I use -addObserverForName: object: queue: usingBlock: for NSNotificationCenter in the -viewDidLoad: method of my view controller, the -dealloc method ends up not being called. (When I remove -addObserverForName: object: queue: usingBlock: , -dealloc is called again.) Using -addObserver: selector: name: object: doesn't seem to have this problem. What am I doing wrong? (My project is using ARC.) Below is an example of my implementation, in case I'm doing something wrong here: [[NSNotificationCenter defaultCenter] addObserverForName:@"Update result" object:nil queue:nil usingBlock:^

This question already has an answer here: NSNotification VS KVO 1 answer Is there any advantage to use KVO instead of the more "generic" (and to my opion more robust) feature of NSNotification s ? I hate KVO with passion, mainly because it forces me to route all KVO notifications through a single handler. I use whatever else available if I have the choice. But KVO has the distinct advantage of being available for many of the classes in the standard library – if you want to observe property changes on some classes from the standard library, KVO might be your only option. There is one very