converting NSData of pdf to NSData of image file

Question

Hihi, I am trying to save pdf files as jpg files. I have a number of urls to query from and these url links are all 1 page pdf files.

var path = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as! String
let urlRequest = NSURLRequest(URL: NSURL(string: downloadUrl[index])!)
NSURLConnection.sendAsynchronousRequest(urlRequest, queue: NSOperationQueue.mainQueue()) { (response, data, error) -> Void in

  var savePath = path.stringByAppendingPathComponent(file_name + ".jpg")

  if let httpResponse = response as? NSHTTPURLResponse {
    if let contentType = httpResponse.allHeaderFields["Content-Type"] as? NSString {
      let fileType = contentType.componentsSeparatedByString("/").last! as! String
      if fileType == "pdf" {

        // convert to jpg before saving!

        NSFileManager.defaultManager().createFileAtPath(savePath, contents: convertedData, attributes: nil)
      } else {
        NSFileManager.defaultManager().createFileAtPath(savePath, contents: data, attributes: nil)
      }

      self.tableView.reloadData()
    }
  }
}

So I am trying to find a solution to convert the data, which is the NSData for the pdf file, into the NSData format for an image file, so that I can save it via the function createFileAtPath with the image NSData as one of the arguments.

Thanks in advance!

UPDATE:

With reference to Rendering a CGPDFPage into a UIImage and David's (thx!) link,

// replace "//convert to jpg before saving!" in the code snippet above
var pdfData = data as CFDataRef
var provider:CGDataProviderRef = CGDataProviderCreateWithCFData(pdfData)
var pdfDoc:CGPDFDocument = CGPDFDocumentCreateWithProvider(provider)
var pdfPage:CGPDFPage = CGPDFDocumentGetPage(pdfDoc, 1)
var pageRect:CGRect = CGPDFPageGetBoxRect(pdfPage, kCGPDFMediaBox)
pageRect.size = CGSizeMake(pageRect.size.width, pageRect.size.height)

println("\(pageRect.width) by \(pageRect.height)")

UIGraphicsBeginImageContext(pageRect.size)
var context:CGContextRef = UIGraphicsGetCurrentContext()
CGContextSaveGState(context)
CGContextTranslateCTM(context, 0.0, pageRect.size.height)
CGContextScaleCTM(context, 1.0, -1.0)
CGContextConcatCTM(context, CGPDFPageGetDrawingTransform(pdfPage, kCGPDFMediaBox, pageRect, 0, true))
CGContextDrawPDFPage(context, pdfPage)
CGContextRestoreGState(context)
let pdfImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

let convertedData:NSData = UIImagePNGRepresentation(pdfImage)
convertedData.writeToFile(savePath, atomically: true)

So the images got saved, but the resolution is bad..Upon further investigation, I found that the width and height of 'pageRect' is now lower than the dimension that it holds when open with GIMP at a ratio of about 0.72. The println statement shows this. This creates the pixelated image of the pdf file. Hmmmm any ideas what caused the dip in dimension conversion n how to solve it?

I would think you need to render the pdf in an image context, then get the UIImage from the context and save that. — Grimxn, May 09 '15 at 09:10
While it's not in swift but objective C, I think this link does exactly what you are looking for (or at least it should point you firmly in the right direction): http://stackoverflow.com/questions/10919075/image-of-the-first-pdf-page-ios-sdk — David van Driessche, May 09 '15 at 17:20

converting NSData of pdf to NSData of image file

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