Timer que se dispara cada media noche

gistfile1.m

    //Update each midnight
    NSCalendar *cal = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
    [cal setTimeZone:[NSTimeZone systemTimeZone]];
    
    NSDateComponents * comp = [cal components:( NSYearCalendarUnit| NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit) fromDate:[NSDate date]];
    
    [comp setMinute:0];
    [comp setHour:0];
    
    NSDate *startOfToday = [cal dateFromComponents:comp];
    NSDate *midnight = [startOfToday dateByAddingTimeInterval:60 * 60 * 24];
    
    ////////////////////////////////////////////////////////////////////////
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"yyyy/MM/dd HH:mm:ss"];
    
    //Optionally for time zone converstions
    [formatter setTimeZone:[NSTimeZone timeZoneWithName:@"..."]];
    
    NSString *stringFromDate = [formatter stringFromDate:midnight];
    
    [formatter release];
    
    NSLog(@"El timer se disparará el %@", stringFromDate);
    
    ////////////////////////////////////////////////////////////////////////
    
    self.midnightTimer = [[NSTimer alloc] initWithFireDate:midnight
                             interval:60 * 60 * 24
                               target:self
                             selector:@selector(timerFired:)
                             userInfo:nil
                              repeats:YES];
    
    NSRunLoop *runloop = [NSRunLoop currentRunLoop];
    [runloop addTimer:self.midnightTimer forMode:NSDefaultRunLoopMode];