A minimal test for a NSNetService bug (rdar://11018654). The TXTRecordData property is never updated.

main.m

//
//  clang main.m -framework Foundation && ./a.out

#import <Foundation/Foundation.h>

/****************************************************************************/
#pragma mark -

@interface Advertiser : NSObject
@end

@implementation Advertiser
{
    NSNetService * _service;
}

- (void) advertise
{
    _service = [[NSNetService alloc] initWithDomain:@"local." type:@"_netservicetest._tcp." name:@"advertisetest" port:12345];
    [_service publish];
    [self updateTXT];
}
- (void) updateTXT
{
    NSString * str = [NSString stringWithFormat:@"%d",(int)[NSDate timeIntervalSinceReferenceDate]];
    NSDictionary * txt = [NSDictionary dictionaryWithObject:str forKey:@"t"];
    NSLog(@"Advertiser: Updating TXT : %@",str);
    _service.TXTRecordData = [NSNetService dataFromTXTRecordDictionary:txt];
    [self performSelector:_cmd withObject:nil afterDelay:5];
}
@end

/****************************************************************************/
#pragma mark -

@interface Browser : NSObject <NSNetServiceDelegate>
@end

@implementation Browser
{
    NSNetService * _service;
}


- (void) browse
{
    _service = [[NSNetService alloc] initWithDomain:@"local." type:@"_netservicetest._tcp." name:@"advertisetest"];
    _service.delegate = self;
    [_service startMonitoring];
//    [_service resolveWithTimeout:10]; // Removing the resolve makes _service.TXTRecordData work correctly. However, not resolving services is kinda useless.
}

- (void)netService:(NSNetService *)sender didUpdateTXTRecordData:(NSData *)data
{
    NSAssert(sender==_service,@"WTF");
    NSString * newStr = [[NSString alloc] initWithData:[[NSNetService dictionaryFromTXTRecordData:data] objectForKey:@"t"] encoding:NSUTF8StringEncoding];
    NSString * oldStr = [[NSString alloc] initWithData:[[NSNetService dictionaryFromTXTRecordData:_service.TXTRecordData] objectForKey:@"t"] encoding:NSUTF8StringEncoding];
    NSLog(@"   Browser: didUpdateTXT : %@",newStr);
    NSLog(@"  _service.TXTRecordData : %@%@",oldStr,[newStr isEqualToString:oldStr]?@"":@" <- WRONG");
}
@end


/****************************************************************************/
#pragma mark -

int main(int argc, const char * argv[])
{

    @autoreleasepool {
        
        Advertiser * advertiser = [Advertiser new];
        [advertiser advertise];
        
        Browser * browser = [Browser new];
        [browser browse];
        
        [[NSRunLoop currentRunLoop] run];
    }
    return 0;
}

output.log

~/gist-2214443 >clang main.m -framework Foundation && ./a.out
2012-03-27 11:46:57.579 a.out[5282:707] Advertiser: Updating TXT : 354534417
2012-03-27 11:46:57.608 a.out[5282:707]    Browser: didUpdateTXT : 354534346
2012-03-27 11:46:57.609 a.out[5282:707]   _service.TXTRecordData : 354534346
2012-03-27 11:46:59.535 a.out[5282:707]    Browser: didUpdateTXT : 354534417
2012-03-27 11:46:59.536 a.out[5282:707]   _service.TXTRecordData : 354534417
2012-03-27 11:47:02.582 a.out[5282:707] Advertiser: Updating TXT : 354534422
2012-03-27 11:47:03.583 a.out[5282:707]    Browser: didUpdateTXT : 354534422
2012-03-27 11:47:03.583 a.out[5282:707]   _service.TXTRecordData : 354534422
2012-03-27 11:47:07.583 a.out[5282:707] Advertiser: Updating TXT : 354534427
2012-03-27 11:47:08.584 a.out[5282:707]    Browser: didUpdateTXT : 354534427
2012-03-27 11:47:08.584 a.out[5282:707]   _service.TXTRecordData : 354534422
2012-03-27 11:47:12.584 a.out[5282:707] Advertiser: Updating TXT : 354534432
2012-03-27 11:47:13.585 a.out[5282:707]    Browser: didUpdateTXT : 354534432
2012-03-27 11:47:13.586 a.out[5282:707]   _service.TXTRecordData : 354534422
2012-03-27 11:47:17.586 a.out[5282:707] Advertiser: Updating TXT : 354534437
2012-03-27 11:47:18.587 a.out[5282:707]    Browser: didUpdateTXT : 354534437
2012-03-27 11:47:18.588 a.out[5282:707]   _service.TXTRecordData : 354534422

have u found a workaround?