i want to create and observer that checks for a change in proximity sensor. i am using this code.
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(proximityChanged:) name:#"UIDeviceProximityStateDidChangeNotification" object:device];
but it give an error of "Use of undeclared identifier 'device'"
please help.
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(proximityChanged:)
name:#"UIDeviceProximityStateDidChangeNotification"
object:nil];
Do like this way you set nil to objcet.
Related
I have an ARC enabled project
There are few observers added in viewDidLoad
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(getSipNotification:) name:#"getSipNotification" object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(syncExtensionData:) name:#"syncExtensionData" object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(showLocalNotification:) name:#"showLocalNotification" object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(outgoingCall:) name:#"outgoingCall" object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(playRingtone) name:#"playRingtone" object:nil];
I want to remove all observers so I added following line in viewDidUnload
[[NSNotificationCenter defaultCenter] removeObserver:self];
Now my question is, is this remove all observers?
If not how can do it?
UPDATE
If I want to remove a single observer how can do it?
Can you help me please.
Yes, It will remove all observers.
[[NSNotificationCenter defaultCenter] removeObserver:self];
And you can remove a particular observer like this...
[[NSNotificationCenter defaultCenter] removeObserver:self name:#"syncExtensionData" object:nil];
In my application i used this notification :
for particular observer remove this way :
-(void)viewWillAppear:(BOOL)animated
{
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(deviceRotatedFeedBackView:) name:UIDeviceOrientationDidChangeNotification object:nil];
}
-(void)deviceRotatedFeedBackView:(NSNotification*)notification
{
//right whetever you want
}
- (void)viewWillDisappear:(BOOL)animated
{
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIDeviceOrientationDidChangeNotification object:nil];
}
may be it will helpful to you.
Yes it'll remove all the observers in your class.
You can use following to remove single observer:
[[NSNotificationCenter defaultCenter] removeObserver:self name:#"getSipNotification" object:nil];
To remove individual observer.
viewDidUnload is deprecated in iOS6 and later, so Your observer never be removed from notification center in iOS6 and later. To remove single observer try
- (void)removeObserver:(id)notificationObserver name:(NSString *)notificationName object:(id)notificationSender
I added a notification with the following code,
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(videoLoadingComplete)
name:MPMovieNaturalSizeAvailableNotification
object:self.streamPlayer];
but it did not enter in the videoLoadingComplete function even after the video stars playing.
You can use following code
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(moviestart:) name:MPMoviePlayerLoadStateDidChangeNotification object:nil];
-(void)moviestart
{
//your code here
}
I have created a device orientation listener to catch when the device is rotated, like so
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(jumpBarButtonPosition)
name:#"UIDeviceOrientationDidChangeNotification" object:nil];
however inside the jumpBarButtonPosition method I have changed from using UIDeviceOrientation to statusBarOrientation, so I am woundering what I could replace UIDeviceOrientationDidChangeNotification with in order to only receive notifications about the statudBarOrientation changes.
Don't type it as a string:#"UIDeviceOrientationDidChangeNotification" use:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(jumpBarButtonPosition)
name:UIDeviceOrientationDidChangeNotification object:nil];
I am trying to call a method within an uiview from AppDelegate using the NSNotificationCenter to no avail..
AppDelegate.m
[[NSNotificationCenter defaultCenter] postNotificationName:#"ProcessDidComplete" object:items];
Then via MainStoryboard, the main view is loaded which controller class is MainViewController
in MainViewController.h viewDidLoad i have
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(ProcessDidComplete:) name:#"ProcessDidComplete" object:nil];
and then the method
- (void) ProcessDidComplete:(NSNotification *)pNotification
but it never gets called.
Thanks for any help!
just change a way..
First add observer
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(ProcessDidComplete:) name:#"ProcessDidComplete" object:nil];
Then Post Notification
[[NSNotificationCenter defaultCenter] postNotificationName:#"ProcessDidComplete" object:items];
Finally remove in viewWillDisappear
[[NSNotificationCenter defaultCenter] removeObserver:self name:#"ProcessDidComplete" object:nil];
Your code looks okay, which makes me wonder where in your app delegate you post the notification?
If you post the notification before you add the observer in the view controlller, then the notification will never be received. Can you not send the message to the main view controller directly, i.e., as a property, rather than using notifications?
Just wanted to note here that iOS notification names are case-sensitive:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(handUpdate:) name:#"scheduleUpdated" object:nil];
will not respond to:
[[NSNotificationCenter defaultCenter] postNotificationName:#"ScheduleUpdated" object:items];
(as I spent the last 20 minutes figuring out...)
I'm trying to get one instance of using NSNotificationCenter with addObserver and postNotificationName but I can't work out why it won't work.
I have 2 lines to code to add the observer and send the message in 2 different classes
[[NSNotificationCenter defaultCenter]addObserver:self selector:#selector(newEventLoaded:) name:#"Event" object:nil];
and
[[NSNotificationCenter defaultCenter]postNotificationName:#"Event" object:self];
If I set the name to nil it works fine becuase it's just a broadcast, when i try and define a notification name the messages never get through.
All my code makes use of NSNotifications like so:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(updateView) name:#"ScanCompleted" object:nil];
[[NSNotificationCenter defaultCenter] postNotificationName:#"ScanCompleted" object:nil];
The first one is registering the notification and the second posting of the notification.
Basically it's all to do with the order of execution. If you've executed postNotificationName before addObserver, then this is an easy problem to have. Use breakpoints and step through the code :)
Your first breakpoint should stop here:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(updateView:) name:#"ScanCompleted" object:nil];
Then here:
[[NSNotificationCenter defaultCenter]postNotificationName:#"ScanCompleted" object:self];
Also, make sure the selector has a colon on. Because it's method signature will be:
- (void)updateView:(NSNotification *)notification;
I had the same problem.
The reason is that I called removeObserver method at
- (void)viewDidDisappear:(BOOL)animated{
NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
[notificationCenter removeObserver:self];
}
So check whether if you had called removeObserver before postNotification.
Tips: You can search the keyword "removeObserver" to find if you had called this function.
Change this:
[[NSNotificationCenter defaultCenter]postNotificationName:#"Event" object:self];
to this:
[[NSNotificationCenter defaultCenter]postNotificationName:#"Event" object:nil];
If your first notification is registered properly, newEventLoaded should be called.
I had a similar issue and my problem was due to the notification being called on another thread. This solved my problem.
dispatch_async(dispatch_get_main_queue(),^{
[[NSNotificationCenter defaultCenter]postNotificationName:#"Event" object:self];
});
Have you tried any other names but #"Event" and nil? Just to be sure, you could define your event names in one file and include that into both notification registration and sending. For example:
Header file:
extern NSString * const NOTE_myEventName;
Source file:
NSString * const NOTE_myEventName = #"MyEventName";
Registration:
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(handleMyEvent:)
name:NOTE_myEventName
object:nil];
Notification sending:
[[NSNotificationCenter defaultCenter]
postNotificationName:NOTE_myEventName object:nil];
I successfully fixed my "NSNotification not being sent when postNotificationName: called" crash.
I found the real bug is in notification message handler.
The postNotificationName and addObserver are all right as the first post of this thread.