how to edit a PDF in objective-c?

Question

i\'m writing an application in objective-c (using cocoa). i have a PDF template, i need to substitute actual values into placeholders in PDF and then save the result into ne

Answer 1

I've found the solution! It connects the power of quartz2d and simplicity of UIGraphics.

NSString *newFilePath = @"path/to/your/newfile.pdf";
NSString *templatePath = @"path/to/your/template.pdf";

//create empty pdf file;
UIGraphicsBeginPDFContextToFile(newFilePath, CGRectMake(0, 0, 792, 612), nil);

CFURLRef url = CFURLCreateWithFileSystemPath (NULL, (CFStringRef)templatePath, kCFURLPOSIXPathStyle, 0);

//open template file
CGPDFDocumentRef templateDocument = CGPDFDocumentCreateWithURL(url);
CFRelease(url);

//get amount of pages in template
size_t count = CGPDFDocumentGetNumberOfPages(templateDocument);

//for each page in template
for (size_t pageNumber = 1; pageNumber <= count; pageNumber++) {
    //get bounds of template page
    CGPDFPageRef templatePage = CGPDFDocumentGetPage(templateDocument, pageNumber);
    CGRect templatePageBounds = CGPDFPageGetBoxRect(templatePage, kCGPDFCropBox);

    //create empty page with corresponding bounds in new document
    UIGraphicsBeginPDFPageWithInfo(templatePageBounds, nil);
    CGContextRef context = UIGraphicsGetCurrentContext();

    //flip context due to different origins
    CGContextTranslateCTM(context, 0.0, templatePageBounds.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);

    //copy content of template page on the corresponding page in new file
    CGContextDrawPDFPage(context, templatePage);

    //flip context back
    CGContextTranslateCTM(context, 0.0, templatePageBounds.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);

    /* Here you can do any drawings */
    [@"Test" drawAtPoint:CGPointMake(200, 300) withFont:[UIFont systemFontOfSize:20]];
}
CGPDFDocumentRelease(templateDocument);
UIGraphicsEndPDFContext();

Answer 2

Probably PDFKit. For some tasks, the high level PDFKit API cannot do what you want, and you might be forced to use the low level CG PDF parsing libraries. They're quite low level, though. They mean really understanding the PDF file format.

Answer 3

I know that the question is about obj-c, but if you are here because of the edit pdf, below there is a solution in Swift 3:

PS: In my solution I needed to edit the document info of the new PDF, so I used the subject parameter to do this.

func createPDF(on path: String?, from templateURL: URL?, with subject: String?) {
    guard let newPDFPath = path,
        let pdfURL = templateURL else { return }

    let options = [(kCGPDFContextSubject as String): subject ?? ""] as CFDictionary

    UIGraphicsBeginPDFContextToFile(newPDFPath, .zero, options as? [AnyHashable : Any])

    let templateDocument = CGPDFDocument(pdfURL as CFURL)
    let pageCount = templateDocument?.numberOfPages ?? 0

    for i in 1...pageCount {

        //get bounds of template page
        if let templatePage = templateDocument?.page(at: i) {
            let templatePageBounds = templatePage.getBoxRect(.cropBox)

            //create empty page with corresponding bounds in new document
            UIGraphicsBeginPDFPageWithInfo(templatePageBounds, nil)
            let context = UIGraphicsGetCurrentContext()

            //flip context due to different origins
            context?.translateBy(x: 0.0, y: templatePageBounds.height)
            context?.scaleBy(x: 1.0, y: -1.0)

            //copy content of template page on the corresponding page in new file
            context?.drawPDFPage(templatePage)

            //flip context back
            context?.translateBy(x: 0.0, y: templatePageBounds.height)
            context?.scaleBy(x: 1.0, y: -1.0)
        }
    }
    UIGraphicsEndPDFContext()
}