NSNotification post on main thread crashes

Question

I have a Notification Manager Class that should post all the notifications on the main thread. But I have some crash reports. The app crashes on this line:

dispatch_sync(dispatch_get_main_queue(), ^{
                [[NSNotificationCenter defaultCenter] postNotificationName:aName object:anObject];

I would like to get an advice how to fix this. Thx in advance

#import "NotificationManager.h"

@interface NotificationManager ()
{
    NSNotificationCenter *center;
}
@end

@implementation NotificationManager

+ (NotificationManager *) sharedInstance
{
    static NotificationManager *instance;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        instance = [[NotificationManager alloc] init];
    });
    return instance;
}

- (void) postNotificationName:(NSString *)aName object:(id)anObject
{
    if (dispatch_get_current_queue() != dispatch_get_main_queue())
    {
        dispatch_sync(dispatch_get_main_queue(), ^{
            [[NSNotificationCenter defaultCenter] postNotificationName:aName object:anObject];
        });
    }
    else
    {
        [[NSNotificationCenter defaultCenter] postNotificationName:aName object:anObject];
    }
}
@end

Crash report:

7   PLR 0x000e5d40  __51-[NotificationManager postNotificationName:object:]_block_invoke in NotificationManager.m on Line 27
8   libdispatch.dylib   0x39a14a88  _dispatch_barrier_sync_f_slow_invoke
9   libdispatch.dylib   0x39a105da  _dispatch_client_callout
10  libdispatch.dylib   0x39a13e44  _dispatch_main_queue_callback_4CF
11  CoreFoundation  0x318cf1b0  __CFRunLoopRun
12  CoreFoundation  0x3184223c  CFRunLoopRunSpecific
13  CoreFoundation  0x318420c8  CFRunLoopRunInMode
14  GraphicsServices    0x3542133a  GSEventRunModal
15  UIKit   0x3375e2b8  UIApplicationMain
16  PLR 0x000c5b4a  main in main.m on Line 9

Answer 1

I can't say whether or not this will fix your problem, but your -postNotificationName:object: method might be better written like this:

- (void) postNotificationName:(NSString *)aName object:(id)anObject
{
    if (![NSThread isMainThread])
    {
        dispatch_sync(dispatch_get_main_queue(), ^{ [self postNotificationName: aName object: anObject]; });
        return;
    }

    [[NSNotificationCenter defaultCenter] postNotificationName:aName object:anObject];
}