I have SKScene controlled by ViewController. Inside this SKScene I have an playing board object (derived from NSObject) with some procedures. I need to post a notification from one of it's procedures (playing board procedures). Inside ViewController I have an observer:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(rowBangEmitAtPosition:) name:#"rowBangN" object:nil];
and inside playing board's procedure I have :
[[NSNotificationCenter defaultCenter] postNotificationName:#"rowBangN" object:self userInfo:#{#"position":point}];
The object is part of SKScene (as variable). But this notification is never triggered. Can someone help me please.
I figured it out - when I put into posting code object:nil instead of object:self, it is working. i don't know why, but it works :).
Thanks to all.
Related
Where can I handle code for pausing game during incoming call. I know about
-(void)applicationWillResignActive:(UIApplication *)application
but during game, how can I call it (I can't call it from SKScene, nor from view controller - only from app delegate, but how can I from there run my piece of code belonging to view controller).
Thank you.
Meanwhile I figured it out, I used NSNotification, here is the line of code, put it inside view controller you want to handle it :
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(pauseGame) name:UIApplicationWillResignActiveNotification object:nil];
I have the following code:
[[NSNotificationCenter defaultCenter] postNotificationName:kNewsfeedFetchCompleted object:self userInfo:userinfo];
only this, no where else. And here's how I set the observer:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(newsfeedFetchCompleted:) name:kNewsfeedFetchCompleted object:nil];
question is when I do one post the newsfeedFetchCompleted is called twice.. how is this even possible?
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
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 continue to try to forward notifications to them.
[[NSNotificationCenter defaultCenter] postNotificationName:kNotificationForbidAdvPost object:nil];
I define postNotificationName:kNotificationForbidAdvPost in a .h file
Im my subclass of NSApplication, I import this .h file. And have a observer of this Notification
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(changeToRecordingStatus) name:kNotificationForbidAdvPost object:nil];
I am sure that the observer was added first, and then post the notification.
And I see the [UINotification default] in Debug. It have same memory address in two part of code.
Is there some mistake I have?
Thanks!
The documentation is pretty clear when it states that
The method specified by
notificationSelector must have one and
only one argument (an instance of
NSNotification).
http://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSNotificationCenter_Class/Reference/Reference.html#//apple_ref/doc/uid/20000219-CHDCIGGB
So, I see your selector you are registering is changeToRecordingStatus when it must be changeToRecordingStatus:
- (void) changeToRecordingStatus: (NSNotification *) notification;
I have try that add a arugument, but it is still not worked.
I create a new project and use a no-argument function to response Notification, it is worked normally.
The reason why I cannot receive the Notification is that a removeObserver method was called at one part which I didn't notice.
Thanks for all your reply.
for some reason this code isn't working in viewDidLoad, but will work in viewWillAppear. Any ideas?
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(wakeUp:)
name:UIApplicationWillEnterForegroundNotification
object:nil];
Thank you
you're definitely sure viewDidLoad is being invoked?
For my case is that I put the removeObserver method inside didReceiveMemoryWarning method, and if I take a picture or do something else, this method fires out of my expect. So, now I always remove notification observer at dealloc stage.