detachNewThreadSelector crashes the app randomly

Question

I am developing an iphone app in which I am extracting RSS feeds and then parsing them.My code is as bellow:

 - (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    NSLog(@"in view did appear");

    if ([stories count] == 0) {
        NSString * path = @"http://www.shire.com/shireplc/rss.jsp";

        //[self parseXMLFileAtURL:path];
        //[self performSelectorInBackground:@selector(parseXMLFileAtURL:) withObject:path];
        NSLog(@"internet is %d",[self checkInternet]);
        if([self checkInternet]==1)
        [NSThread detachNewThreadSelector:@selector(parseXMLFileAtURL:) 
                              toTarget:self withObject:path];

}
}

 - (void)parseXMLFileAtURL:(NSString *)URL
  { 
  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
  stories = [[NSMutableArray alloc] init];

  //you must then convert the path to a proper NSURL or it won't work
  NSURL *xmlURL = [NSURL URLWithString:URL];

  // here, for some reason you have to use NSClassFromString when trying to alloc NSXMLParser, otherwise you will get an object not found error
  // this may be necessary only for the toolchain
  rssParser = [[NSXMLParser alloc] initWithContentsOfURL:xmlURL];

  // Set self as the delegate of the parser so that it will receive the parser delegate methods callbacks.
[rssParser setDelegate:self];

// Depending on the XML document you're parsing, you may want to enable these features of NSXMLParser.
[rssParser setShouldProcessNamespaces:NO];
[rssParser setShouldReportNamespacePrefixes:NO];
[rssParser setShouldResolveExternalEntities:NO];

[rssParser parse];

 [pool release];

}

Can anyone tell me where I am going wrong? My log is as bellow: log: [Switching to thread 12803] [Switching to thread 12035] 2011-05-10 11:31:30.932 Annual Report[454:490b] found file and started parsing [Switching to thread 14339] 2011-05-10 11:32:04.742 Annual Report[454:640b] found file and started parsing [Switching to thread 13827] [Switching to thread 13827] Program received signal: “EXC_BAD_ACCESS”.

gdb stack trace at 'putpkt: write failed':
0   gdb-arm-apple-darwin                0x0019026b remote_backtrace_self + 54

Answer 1

Finally,I used a flag to check if the view is appeared or not(by making flag true in viewdidAppear) and if the view is not appearing,don't run the thread function.That solved the problem!!!