title: Working with multi-page images in an NSImage
body: <p>I'm working on an image viewer application (OSX) and currently it can load and view images, but I need to be able to view multi-page PDFs and TIFFs. I'll have next/previous page buttons, etc.</p>
  
  <p>Now, with PDF, I expect to use an NSPDFImageRep. This will let me set the current page and draw the current page etc.</p>
  
  <p>However, I don't see an NSTIFFImageRep, and the NSImageRep class doesn't seem to have any way of dealing with pages...</p>
  
  <p>ETA (more specifics on my question): How do I work with a multi-page TIFF? In C, I used a CGImageSource which let me get the nth page. I don't see an equivalent for TIFFs in objective C. </p>
  
  <p>thanks. </p>