post = @"string";

- (IBAction)getBill:(id) sender;
{
    NSURL *url = [NSURL URLWithString:@"the url"];
    NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
    NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];

    request = [[NSMutableURLRequest alloc] initWithURL:url];
    [request setHTTPMethod:@"POST"];
    [request setValue:postLength forHTTPHeaderField:@"Content-Length"];
    [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
    [request setHTTPBody:[post dataUsingEncoding:NSASCIIStringEncoding]];

    requestURL = [NSString stringWithFormat:@"%@",request];

    QLPreviewController *previewController = [[QLPreviewController alloc] init];
    previewController.dataSource = self;
    previewController.currentPreviewItemIndex = 0;
    [self presentModalViewController:previewController animated:YES];
}

-(NSInteger) numberOfPreviewItemsInPreviewController:(QLPreviewController *)previewController
{
    return 1;
}

-(id)previewController:(QLPreviewController *)previewController previewItemAtIndex:       (NSInteger)index
{
    return requestURL;
}