Saving a PDF to Disk Using Quartz

Question

I am trying to draw a pdf page in the context of a pdf and then save it to disk. I can’t understand what’s wrong. Can someone give me some pointers. Thank.

- (void)testQuartz:(NSData *)pdfDocumentData
{   
    //Create the pdf document reference
    CGDataProviderRef dataProvider = CGDataProviderCreateWithCFData((CFDataRef)pdfDocumentData);
    CGPDFDocumentRef document = CGPDFDocumentCreateWithProvider(dataProvider);
    CGDataProviderRelease(dataProvider); //Release the data provider

    //Create the pdf context
    CGPDFPageRef page = CGPDFDocumentGetPage(document, 0);
    CGRect pageRect = CGPDFPageGetBoxRect(page, kCGPDFMediaBox);
    CFMutableDataRef mutableData = CFDataCreateMutable(NULL, 0);

    CGDataConsumerRef dataConsumer = CGDataConsumerCreateWithCFData(mutableData);
    CGContextRef pdfContext = CGPDFContextCreate(dataConsumer, &pageRect, NULL);

    if (CGPDFDocumentGetNumberOfPages(document) > 0)
    {       
        //Draw the page onto the new context
        page = CGPDFDocumentGetPage(document, 0);
        CGContextDrawPDFPage(pdfContext, page);
    }
    else
    {
        NSLog(@"Failed to create the document");
    }

    //Write to disk
    [(NSMutableData *)mutableData writeToFile:@"/Users/David/Desktop/test.pdf" atomically:YES];

    //Clean up
    CGDataConsumerRelease(dataConsumer);
    CFRelease(mutableData);
    CGPDFDocumentRelease(document);
}

Answer 1

So, I found 3 things wrong.

• PDF pages start at 1, not 0.
• You must specify the pdf context when the page starts and ends.
• Release the pdf context before writing data to disk. This is for some reason the key.

Here is the corrected code that works.

- (void)testQuartz:(NSData *)pdfDocumentData
{       
    //Create the pdf document reference
    CGDataProviderRef dataProvider = CGDataProviderCreateWithCFData((CFDataRef)pdfDocumentData);
    CGPDFDocumentRef document = CGPDFDocumentCreateWithProvider(dataProvider);

    //Create the pdf context
    CGPDFPageRef page = CGPDFDocumentGetPage(document, 1); //Pages are numbered starting at 1
    CGRect pageRect = CGPDFPageGetBoxRect(page, kCGPDFMediaBox);
    CFMutableDataRef mutableData = CFDataCreateMutable(NULL, 0);

    //NSLog(@"w:%2.2f, h:%2.2f",pageRect.size.width, pageRect.size.height);
    CGDataConsumerRef dataConsumer = CGDataConsumerCreateWithCFData(mutableData);
    CGContextRef pdfContext = CGPDFContextCreate(dataConsumer, &pageRect, NULL);


    if (CGPDFDocumentGetNumberOfPages(document) > 0)
    {       
        //Draw the page onto the new context
        //page = CGPDFDocumentGetPage(document, 1); //Pages are numbered starting at 1

        CGPDFContextBeginPage(pdfContext, NULL);
        CGContextDrawPDFPage(pdfContext, page);
        CGPDFContextEndPage(pdfContext);
    }
    else
    {
        NSLog(@"Failed to create the document");
    }

    CGContextRelease(pdfContext); //Release before writing data to disk.

    //Write to disk
    [(NSData *)mutableData writeToFile:@"/Users/David/Desktop/test.pdf" atomically:YES];

    //Clean up
    CGDataProviderRelease(dataProvider); //Release the data provider
    CGDataConsumerRelease(dataConsumer);
    CGPDFDocumentRelease(document);
    CFRelease(mutableData);
}