I have following error msg in console when using NSThread "Tried to obtain the web lock from a thread other than the main thread or the web thread. This may be a result of calling to UIKit from a secondary thread. Crashing now..."

I have submit my sample code here

- (void)viewDidLoad {

    appDeleg = (NewAshley_MedisonAppDelegate *)[[UIApplication sharedApplication] delegate];
    [[self tblView1] setRowHeight:80.0];
    [super viewDidLoad];
    self.title = @"Under Ground";


    [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
    [NSThread detachNewThreadSelector:@selector(CallParser) toTarget:self withObject:nil];

}

-(void)CallParser {


    Parsing *parsing = [[Parsing alloc] init];
    [parsing DownloadAndParseUnderground];

    [parsing release];
    [self Update_View];
    //[myIndicator stopAnimating];
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;




}

here "DownloadAndParseUnderground" is the method of downloding data from the rss feed and

-(void) Update_View{


    [self.tblView1 reloadData];
}

when Update_View method is called the tableView reload Data and in the cellForRowAtIndexPath create error and not display custom cell

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {


    static NSString *CellIdentifier = @"Cell";

    CustomTableviewCell *cell = (CustomTableviewCell *) [tblView1 dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil) {

        [[NSBundle mainBundle] loadNibNamed:@"customCell"
                                      owner:self 
                                    options:nil];

        cell = objCustCell; 
        objCustCell = nil;

    }