iPDFdev Tips & Tricks for PDF development

bolosati
April 29th, 2011 - 07:47

It would be possible to add a digital signature (certificate, hash, etc) to a PDF on the iPhone?

Congratulations on the blog

Jane
August 1st, 2011 - 21:10

We’re trying to save the ink in a separate context and send it up to the server with a document id where it will be combined with the original document. How can we determine what page of the PDF document the user is viewing?

Vipin
August 29th, 2012 - 06:22

Can you provide a code that converts SVG File to PDF.

Chris
November 17th, 2013 - 10:38

I am also having difficulty saving multiple images as a single pdf. I loop through the images and apply the “begin”, “draw”, and “end” methods to each image, but the resulting pdf is only one of the images.

////////////////////////////////////////////////////////////////////////////////////////////////////////////
+(NSData*)convertArrayOfImagesToPDF: (NSArray*)theImages withResolution: (double)resolution {
if (resolution <= 0) {
return nil;
}

CGSize pageSize = CGSizeMake(612, 792);

NSMutableData *pdfFile = [[NSMutableData alloc] init];
CGDataConsumerRef pdfConsumer = CGDataConsumerCreateWithCFData((CFMutableDataRef)pdfFile);

// CGContextRef pdfContext = nil;

for (int i=0; i 1) || (sy > 1)) {
double maxScale = sx > sy ? sx : sy;
imageWidth = imageWidth / maxScale;
imageHeight = imageHeight / maxScale;
}

// Put the image in the top left corner of the bounding rectangle
CGRect imageBox = CGRectMake(0, 0 + pageSize.height – imageHeight, imageWidth, imageHeight);

CGRect mediaBox = CGRectMake(0, 0, pageSize.width, pageSize.height);
CGContextRef pdfContext = CGPDFContextCreate(pdfConsumer, &mediaBox, NULL);

CGContextBeginPage(pdfContext, &mediaBox);
CGContextDrawImage(pdfContext, imageBox, [image CGImage]);
CGContextEndPage(pdfContext);
CGContextRelease(pdfContext);

}

CGDataConsumerRelease(pdfConsumer);

return pdfFile;
}

Nick
May 15th, 2014 - 19:33

I’m using this code in a Cocoa app to see what I can do with some large images I have. This works very well when the image is 72 DPI but there’s a lot of detail lost when the DPI is higher. I have a large map that was scanned with 400 DPI that I’m trying to convert to PDF. Any ideas on how to handle that?

Thank you for any thoughts you have,
Nick

Thanh Nguyen
November 20th, 2015 - 11:28

Great article! I want to add electronic signature (handwriting signature) into a PDF. Do you think if I can do it directly with the quartz instead of using commercial PDF lib? I am sorry for the silly question because I am new to iOS development.

Best,
Thanh

Mike Lima
October 10th, 2016 - 02:13

I think you may have these lines wrong

double pageWidth = image.size.width * image.scale * 72 / horzRes;
double pageHeight = image.size.height * image.scale * 72 / vertRes;

on this code horzRez and vertRez are divisors. That means that if you increase the resolution your final variables will have smaller values. As far as I know, higher resolutions will always give bigger contexts.

so, I suppose these lines have to be

double pageWidth = image.size.width * image.scale * horzRes / 72;
double pageHeight = image.size.height * image.scale * vertRes / 72;

isn’t it?