gistfile1.m

int main(int argc, char *argv[])
{
   int retVal = 0;

   NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
   {
#if YOURAPP_DEBUG_LOG
      // Redirect stdout to a file in ~/Documents
      
      NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
      [dateFormatter setDateFormat: @"yyyyMMd-Hms"];
      
      NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
      if (paths && [paths count] != 0) {
         NSString* path = [[paths objectAtIndex: 0] stringByAppendingPathComponent:
            [NSString stringWithFormat: @"/YourApp-%@.txt", [dateFormatter stringFromDate: [NSDate date]]]];
         if ([[NSFileManager defaultManager] createFileAtPath: path contents: [NSData data] attributes: nil] == NO) {
            NSLog(@"Could create %@: %s", path, strerror(errno));
         } else {
            NSFileHandle* fileHandle = [NSFileHandle fileHandleForWritingAtPath: path];
            if (fileHandle != nil) {
               if (dup2([fileHandle fileDescriptor], STDERR_FILENO) == -1) {
                  NSLog(@"Unable to redirect stderr to %@: %s", path, strerror(errno));
               } else {
                  NSLog(@"This is the start of the log file for Your App");
               }
            }
         }
      }
#endif

      // Start the application
   
      retVal = UIApplicationMain(argc, argv, nil, nil);
    }
    [pool release];
   
    return retVal;
}