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 new PDF.

how can i do it? which library should i use?

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();