CODEWITHSUNDEEP
iosobjective-csocketsnsnotificationcenter
Andy
Andy

Reputation: 770

NSNotification object being sent is (null)?

When I receive data from a socket and pass the data to another VC via NSNotificationCenter, the passed object always logs (null), despite the object being present in the other class.

there is where I pass the data through.

UPDATED:

   -(void) initSIOSocket {
    [SIOSocket socketWithHost:@"http://192.168.1.4:8080" response:^(SIOSocket *socket) {

            self.socket = socket;
            NSLog(@"%@ from initSIOSocket", self.socket);

            [self.socket on:@"q_update_B" callback:^(NSArray *args) {


            NSArray *tracks = [args objectAtIndex:0];

            [[NSNotificationCenter defaultCenter] postNotificationName:@"qUpdateB" object:nil userInfo:[NSDictionary dictionaryWithObject:tracks forKey:@"tracksData"]];

        }];

..

- (void)receiveUpdateBNotification:(NSNotification *)notification
{
    // Do parse respone data method and update yourTableViewData

    NSArray *tracks = [[notification userInfo] objectForKey:@"tracksData"];
    NSLog(@"%@", tracks);
    self.tracks = tracks;
    [self.tableView reloadData];
}

Console is STILL logging as (null) object. The notification is successful, no data is sent.

Upvotes: 0

Views: 1041

Answers (2)

Andy
Andy

Reputation: 770

I needed to use my Singleton to pass the data using the NSNotificationCenter, like so. 

-(void) initSIOSocket {
    [SIOSocket socketWithHost:@"http://192.168.1.4:8080" response:^(SIOSocket *socket) {

            self.socket = socket;
            NSLog(@"%@ from initSIOSocket", self.socket);

            [self.socket on:@"q_update_B" callback:^(NSArray *args) {


            NSArray *tracks = [args objectAtIndex:0];
            self.setListTracks = tracks;
            [[NSNotificationCenter defaultCenter] postNotificationName:@"qUpdateB" object:nil];

        }];


    }];

}

..

- (void)receiveUpdateBNotification:(NSNotification *)notification
{
    if ([[notification name] isEqualToString:@"qUpdateB"])
        NSLog (@"Successfully received the test notification!");
    // Do parse respone data method and update yourTableViewData
    NSArray *tracks = [[SocketKeeperSingleton sharedInstance]setListTracks];
    self.tracks = tracks;
    [self.tableView reloadData];
}

Upvotes: -1

Midhun MP
Midhun MP

Reputation: 107141

For passing data using NSNotification you need to use the userInfo dictionary.

Post it like:

[[NSNotificationCenter defaultCenter] postNotificationName:@"qUpdateB" object:nil userInfo:[NSDictionary dictionaryWithObject:tracks forKey:@"MyData"]];

And retrieve it using:

- (void)receiveUpdateBNotification:(NSNotification *)notification
{
    self.tracks = [[notification userInfo] objectForKey:@"MyData"];
    [self.tableView reloadData];
}

Object property is not intended for passing data.

object

The object associated with the notification. (read-only) Declaration

@property(readonly, retain) id object Discussion;

This is often the object that posted this notification. It may be nil.

Typically you use this method to find out what object a notification applies to when you receive a notification.

For example, suppose you’ve registered an object to receive the message handlePortDeath: when the “PortInvalid” notification is posted to the notification center and that handlePortDeath: needs to access the object monitoring the port that is now invalid. handlePortDeath: can retrieve that object as shown here:

- (void)handlePortDeath:(NSNotification *)notification
{
  ...
  [self reclaimResourcesForPort:notification.object];
  ...
}

Reference

Upvotes: 2

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