-( void )thumbnailOfPDF{ NSURL * pdfFileUrl = [ NSURL fileURLWithPath :[[ NSBundle mainBundle ] pathForResource : @"test" ofType : @"pdf" ]]; CGPDFDocumentRef pdf = CGPDFDocumentCreateWithURL (( CFURLRef ) CFBridgingRetain (pdfFileUrl)); CGPDFPageRef page; CGRect aRect = CGRectMake ( 0 , 0 , 70 , 100 ); // thumbnail size UIGraphicsBeginImageContext (aRect. size ); CGContextRef context = UIGraphicsGetCurrentContext (); UIImage* thumbnailImage; NSUInteger totalNum = CGPDFDocumentGetNumberOfPages (pdf); [ self . thumbScrollView setContentSize : CGSizeMake ( self . thumbScrollView . frame . size . width , totalNum* 100 )]; for ( int i = 0 ; i < totalNum; i++ ) { ...