Unable to receive notification - ios

Question

I try to send local notification. Here some code for class sending the notification:
#interface Sender : UIView
{
NSInteger itemID;
}
#implementation Sender
-(void) changedProperty
{
[[NSNotificationCenter defaultCenter] postNotificationName:#"NotificationName" object:NULL];
}
And here the code to receive this notification:
#interface Listener : UIViewController
{
}
#implementation Listener
- (void)viewDidLoad
{
[super viewDidLoad];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(selectedItem:) name:#"NotificationName" object:NULL];
}
- (void)viewDidUnload
{
[super viewDidUnload];
[[NSNotificationCenter defaultCenter] removeObserver:self name:#"NotificationName" object:NULL];
}
-(void) selectedItem:(NSNotification *) notification
{
// some actions
}
But this code doesn't work. Debugging I see how postNotificationName: object works but the method selectedItem: doesn't call
UPDATE.
Here is more code. Maybe this will help.
extern const NSString* selectItemNotificationName;
#interface vRoomSelectorItem : UIView
{
RoomSelectorItemBackground backgroundType;
NSInteger itemID;
}
#property NSInteger itemID;
-(void) setBackgroundType:(RoomSelectorItemBackground) backgroundType;
#interface vRoomSelectorItem ()
#property RoomSelectorItemBackground backgroundType;
#end
#implementation vRoomSelectorItem
const NSString* selectItemNotificationName = #"Reservation.SelectRoom";
-(RoomSelectorItemBackground) backgroundType
{
return backgroundType;
}
-(void) setBackgroundType:(RoomSelectorItemBackground)value
{
if(backgroundType != value)
{
backgroundType = value;
[self changedBackgroundType];
}
}
-(void) changedBackgroundType
{
if(backgroundType == RoomSelectorItemFilled)
{
// animation
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] postNotificationName:(NSString*)selectItemNotificationName object:NULL userInfo:[[NSDictionary alloc] initWithObjectsAndKeys:[NSNumber numberWithInteger:itemID], #"ID", NULL]];
});
}
else
// reverse animation
}
#import "vRoomSelectorItem.h"
#interface vcReservationSelectRoom : UIViewController
{
NSMutableArray* arraySelectorItems;
}
#implementation vcReservationSelectRoom
- (void)viewDidLoad
{
[super viewDidLoad];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(selectedItem:) name:(NSString*)selectItemNotificationName object:NULL];
for(NSInteger i = 1; i <= SELECTOR_ITEM_COUNT; ++i)
{
vRoomSelectorItem* newItem = [[vRoomSelectorItem alloc] initWithFrame:CGRectMake(/*coordinates*/)];
[self.view addSubview:newItem];
[newItem setBackgroundType:RoomSelectorItemTransparent];
[newItem setItemID:i];
[arraySelectorItems addObject:newItem];
newItem = NULL;
}
}
-(void) selectedItem:(NSNotification *) notification
{
// some actions
}
-(void) dealloc
{
arraySelectorItems = NULL;
[[NSNotificationCenter defaultCenter] removeObserver:self name:(NSString*)selectItemNotificationName object:NULL];
}
#end

Answer 1

From your code in the quetion I think you can try this:
- (void)viewDidLoad
{
[super viewDidLoad];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(selectedItem:) name:#"NotificationName" object:NULL];
[self.view changedProperty]; // method of your Sender class
}

Answer 2

It seems like your code should work. Make sure the notification is on the main thread and the workflow is as follows:
Add listener to notification center
Initiate sender
Send notification
You can be sure that it is on the main thread with:
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] post...];
});
Couple things I would change:
remove yourself from NSNotificationCenter in -(void)dealloc instead
of -(void)viewDidUnload. viewDidUnload will be deprecated, and
dealloc could get called without viewDidUnload.
For Notifications, I like to store the name in an external constant
to make sure that I don't typo the string:
//header.h
extern NSString *const notificationName;
//implementation.m
NSString *const notificationName = #"notification";

Answer 3

Ok, I've solved the problem. The piece of code above is not enough to understand, why it has not been working. The object of class vcReservationSelectRoom was temporary and it had been destroyed before sending notification from any vRoomSelectorItem. Sorry for my mistake of not showing enough code to solve this problem. And thank you all for helping.