Question

I have a solution for a notification problem which works well, but I’m afraid might be a bad idea.

I have a notification that needs to be handled by each instance of a class and by the class itself. To handle this, I’m registering for a notification by both the class and instances of the class. Because it’s the exact same notification, I’ve named the class and instance method the same. This follows the standard we’ve set for how notification handlers are named.

Is this a bad idea? Is there some hidden got’ca that I’m missing. Will I be confusing the heck out of future developers?

+ (void)initialize
{
    if (self == [SICOHTTPClient class]) {
        [[self notificationCenter] addObserver:self
                                      selector:@selector(authorizationDidChangeNotification:)
                                          name:SICOJSONRequestOperationAuthorizationDidChangeNotification
                                        object:nil];
    }
}

- (id)initWithBaseURL:(NSURL *)url
{
    self = [super initWithBaseURL:url];

    if (self) {
        self.parameterEncoding = AFJSONParameterEncoding;
        [self registerHTTPOperationClass:[SICOJSONRequestOperation class]];
        [self setDefaultHeader:@"Accept" value:@"application/json"];

        if ([[self class] defaultAuthorization])
            [self setDefaultHeader:@"Authorization" value:[[self class] defaultAuthorization]];

        [[[self class] notificationCenter] addObserver:self
                                              selector:@selector(authorizationDidChangeNotification:)
                                                  name:SICOJSONRequestOperationAuthorizationDidChangeNotification
                                                object:nil];
    }

    return self;
}

- (void)dealloc
{
    [[[self class] notificationCenter] removeObserver:self
                                                 name:SICOJSONRequestOperationAuthorizationDidChangeNotification
                                               object:nil];
}

#pragma mark Notifications

- (void)authorizationDidChangeNotification:(NSNotification *)notification
{
    NSString *authorization = notification.userInfo[SICOJSONRequestOperationAuthorizationKey];

    if ([authorization isKindOfClass:[NSString class]]) {
        [self setDefaultHeader:@"Authorization" value:authorization];
    } else {
        [self clearAuthorizationHeader];
    }
}

+ (void)authorizationDidChangeNotification:(NSNotification *)notification
{
    NSString *authorization = notification.userInfo[SICOJSONRequestOperationAuthorizationKey];

    if ([authorization isKindOfClass:[NSString class]]) {
        [self setDefaultAuthorization:authorization];
    } else {
        [self setDefaultAuthorization:nil];
    }
}

Answer 1

This is what code comments are for 🙂

There’s no problem in Objective C with a class method and instance method having the same name.

I would suggest either:

• amend your notification method name spec to handle this (and then handle the class notification with a different appropriately named method), or

• add appropriate comment to explain what’s happening for benefit of future potentially confused developers