Creating pdf Thumbnail in iphone

I am new to Objective-c iPhone programming. I have an application in which I display a PDF in my UIWebView successfully, but now I want to create a thumbnail of my PDF. My PDF is stored in my resource folder.

So please give me code for how I can show a thumbnail of my PDF. My code is for displaying PDF is which is taken in button function:

-(void)show:(id)sender {

    pdfView.autoresizesSubviews = NO;
    pdfView.scalesPageToFit=YES;
    pdfView.autoresizingMask=(UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth);
    [pdfView setDelegate:self];

    NSString *path = [[NSBundle mainBundle] pathForResource:@"com" ofType:@"pdf"];
    NSLog(@"Path of res is%@",path);
    NSURL *url = [NSURL fileURLWithPath:path];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    [pdfView loadRequest:request];
}