Convert PDF pages to images with COCOA

Question

Hi,

I am having problem with PDF conversion to images. I would like to create an image file for every page in PDF document.

This is the code I am using and works fine. Every page gets converted into the image, but I have problem with image resolution. I don't know how to set the resolution of the output images. Can someone help me out?

NSData *pdfData = [NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://localhost/test/test.pdf"]];


NSPDFImageRep *img = [NSPDFImageRep imageRepWithData:pdfData]; 
 NSFileManager *fileManager = [NSFileManager defaultManager];
 int count = [img pageCount]; 
 for(int i = 0 ; i < count ; i++) { 
  [img setCurrentPage:i]; 
  NSImage *temp = [[NSImage alloc] init]; 
  [temp addRepresentation:img]; 
  NSBitmapImageRep *rep = [NSBitmapImageRep imageRepWithData:[temp TIFFRepresentation]]; 
  NSData *finalData = [rep representationUsingType:NSJPEGFileType properties:nil]; 
  NSString *pageName = [NSString stringWithFormat:@"Page_%d.jpg", [img currentPage]]; 
  [fileManager createFileAtPath:[NSString stringWithFormat:@"%@/%@", @"/Users/mac/Desktop/", pageName] contents:finalData attributes:nil];
 }

Thanks a lot!

Answer 1

Since NSPDFImageRep is a subclass of NSImageRep, couldn't you use the [NSImageRep drawInRect:] method?

Link: http://developer.apple.com/mac/library/documentation/cocoa/reference/ApplicationKit/Classes/NSImageRep_Class/Reference/Reference.html#//apple_ref/doc/uid/20000346-drawInRect_

Answer 2

The simplest way would be to use the ImageIO framework. Feed the PDF data to an image source to get a CGImage; feed that object to an image destination to generate (and optionally save in the same step) the JPEG data. In the latter step, you can specify the resolution among the image properties; see “Individual Image Properties” in the documentation.

Don't forget to finalize your destination. It's vital.