CFRunLoopRun() and NSTimer -> segmentation fault

Thanks in advance to anyone who is helping me.

I've a simple daemon. I allocate a class and then start a scheduled & repeating NSTimer:

[NSTimer scheduledTimerWithTimeInterval:3.0 target:self selector:@selector(usage3GviaSysctl) userInfo:nil repeats:YES];

then I call CFRunLoopRun() so that my daemon will stay alive.

int main(int argc, char *argv[])
{
   NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
   signal(SIGTERM, (sig_t)SIGTERM_handler);

   helper = [[NMDaemonHelper alloc] init];
   [helper startNotificationServer];
   CFRunLoopRun();

   NSLog(@"NMDAEMON: will exit");
   [pool release];
   return 0;
}

Now the problem is that after the timer fires I get a segfault. bt:

objc_msgSend
__NSFireTimer
__CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__
__CFRunLoopDoTImer
__CFRunLoopRun
CFRunLoopRunSpecific

other ways to start the timer didn't work either. for example:

NSTimer *timeUpdateTimer = [[NSTimer alloc] initWithFireDate:[NSDate date] interval:1 target:self selector:@selector(usage3GviaSysctl) userInfo:nil repeats:YES]; 
[[NSRunLoop currentRunLoop] addTimer:timeUpdateTimer forMode:NSDefaultRunLoopMode];

Has anybody an idea what's going (wr)on(g)?

Solution

My guess is your selector doesn't have the right format ... needs to have an NSTimer argument, so your selector has to have the ":" in it, so @selector(usage3GviaSysctl:).

... I tried it myself and seems to works so here's my code in case it was something else:

#import <Foundation/Foundation.h>

@interface NMDaemonHelper : NSObject {
    NSTimer *_aTimer;
}
- (void)startNotificationServer;
@end

@implementation NMDaemonHelper

- (void)dealloc {
    [_aTimer invalidate];
    [super dealloc];
}

- (void)startNotificationServer {
    _aTimer = [NSTimer scheduledTimerWithTimeInterval:3.0 target:self selector:@selector(usage3GviaSysctl:) userInfo:nil repeats:YES];
}

- (void)usage3GviaSysctl:(NSTimer *)aTimer {
    NSLog(@"timer fired");
}

@end

void SIGTERM_handler(int signum) {
    NSLog(@"SIGTERM_handler");
}

int main(int argc, char *argv[]) {
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    signal(SIGTERM, (sig_t)SIGTERM_handler);

    NMDaemonHelper *helper = [[NMDaemonHelper alloc] init];
    [helper startNotificationServer];
    CFRunLoopRun();

    [helper release];
    NSLog(@"NMDAEMON: will exit");
    [pool release];
    return 0;
}

... and output is:

pho0$ ./climac
2011-03-25 18:43:36.723 climac[2833:903] timer fired
2011-03-25 18:43:39.723 climac[2833:903] timer fired
2011-03-25 18:43:42.722 climac[2833:903] timer fired
2011-03-25 18:43:45.722 climac[2833:903] timer fired
2011-03-25 18:43:48.722 climac[2833:903] timer fired
2011-03-25 18:43:51.722 climac[2833:903] timer fired