NSNotificationCenter: addObserver that is not self

问题:

Here's the question:

Can one View Controller add another View Controller as an Observer to the defaultCenter before the second view has been loaded?

I have a model class that creates a NSURLSession, grabs some data, builds an array, and sends notifications that it's done (along with a pointer to the array).

My app loads with a Map View that instantiates the model, calls the method to create the array, listens for the notification, and drops pins using the array.

I have a Table View tab that I want to load using the array built by the map.

Can my Map View add my Table View Controller as an observer before the Table View is loaded?

Something like:

[[NSNotificationCenter defaultCenter] addObserver: TableViewController ... 

Thanks for any insight. I'm figuring this out as I go.

-----------------EDIT--------------------

viewDidLoad from MapViewController:

- (void)viewDidLoad {   [super viewDidLoad];   _mapView.delegate = self;   _model = [[WikiModel alloc] init];   _lastArticleUpdateLocation = [[CLLocation alloc] initWithLatitude:0 longitude:0];   _lastUpdateUserLocation    = [[CLLocation alloc] initWithLatitude:0 longitude:0];    // Listen for WikiModel to release updates.   [[NSNotificationCenter defaultCenter] addObserver:self                                            selector:@selector(reloadData:)                                                name:@"Array Complete"                                              object:_model];  //table view listener attempt ... UITableViewController *tvc = [self.storyboard instantiateViewControllerWithIdentifier:@"tableViewController"];  [[NSNotificationCenter defaultCenter] addObserver:tvc                                          selector: @selector(updateDataSource:)                                              name:@"Array Complete"                                            object:nil]; [self.navigationController pushViewController:tvc animated:YES]; 

}

From the TableViewController:

- (void)viewDidLoad {   [super viewDidLoad];    // Listen for WikiModel to release updates.     /*   [[NSNotificationCenter defaultCenter] addObserver:self                                            selector:@selector(updateDataSource:)                                                name:@"Array Complete"                                              object:nil];*/ }  -(void)updateDataSource:(NSNotification *)notification {   _wikiEntries = [[notification userInfo] objectForKey:@"wikiEntryArray"];   [self.tableView reloadData];     NSLog(@"************received***********"); } 

回答1:

This is possible as long as you pass the pointer to your view controller as the observer. Here's an example:

//Go to the detail view VC2ViewController *dvc = [self.storyboard instantiateViewControllerWithIdentifier:@"VC2ViewController"]; //ID specified in the storyboard [[NSNotificationCenter defaultCenter] addObserver:dvc selector:@selector(notificationReceived:) name:@"MyNotification" object:nil]; [self.navigationController pushViewController:dvc animated:YES]; 

Then, you can post your notification as usual:

[[NSNotificationCenter defaultCenter] postNotificationName:@"MyNotification" object:nil]; 

I just tested the above code and it worked fine for me, the following function was called in my detail view controller:

-(void)notificationReceived:(NSNotification *)notification {      NSLog(@"RECEIVED"); } 

文章来源: NSNotificationCenter: addObserver that is not self