Scroll To Specific Page using CGPDF - ios

Question

I am struck with this past two days i don't find any proper documents relating to CGPDF. I tried every possible way but i failed. Here is what i am trying to do. I have a PDF to display and i am displaying it in a UIWebView. I have created a CORE GRAPHICS PDF document reference using the path where the pdf is located (NSURL). I created a UIView over it and handled a single touch event. When the PDF loads and user clicks the view i want the page to scroll to a specific page. I know this can be done via calculating Page height and width. I wanted to know if there is a Way in CGPDF to pass a page number and it scroll to the relevant page. Below is my Code
- (void)viewDidLoad
{
[super viewDidLoad];
// set the pdfPafeHeight to -1 so it gets calculated.
self.pdfPageHeight = -1;
// set the delegate of the UIWebView's underlying UIScrollView to self.
self.webView.scrollView.delegate = self;
// create an NSURLRequest to load the PDF file included with the project
_filePath = [[NSBundle mainBundle] pathForResource:#"Sample" ofType:#"pdf"];
_url = [NSURL fileURLWithPath:_filePath isDirectory:NO];
_urlRequest = [NSURLRequest requestWithURL:_url];
// create a Core Graphics PDF Document ref using the same NSURL
_pdf = CGPDFDocumentCreateWithURL((CFURLRef) _url);
// use CGPDFDocumentGetNumberOfPages to get the number of pages in the document
self.pdfPageCount = (int)CGPDFDocumentGetNumberOfPages(_pdf);
// load the PDF file into the UIWebVie
UITapGestureRecognizer *singleFingerTap =
[[UITapGestureRecognizer alloc] initWithTarget:self
action:#selector(handleSingleTap:)];
[self.view addGestureRecognizer:singleFingerTap];
[self.webView loadRequest:_urlRequest];
}
HERE IS HOW I WANTED HANDLE SINGLE TAP ON UIVIEW. I just wanted to know if there is any method in CGPDF to scroll to specific page when i pass a page number to it
- (void)handleSingleTap:(UITapGestureRecognizer *)recognizer {
}

Answer 1

There's no API for what you're trying to achieve, and even if you're able to use private API if this app is just for Enterprise install and doesn't need to go to the App Store - this will be tricky and any workaround will likely break with a major iOS version update. If you want to go this route, you can introspect the view controller hierarchy and will find that Apple internally has a framework called CorePDF which has an internal private API that you might be able to access - but be careful and know that this is not a solution for App Store apps.
The alternative is to start from scratch and use CGContextDrawPDFPage to draw PDF pages, building your own cache, scroll views and view controllers+gesture handling. We did that with the commercial PSPDFKit SDK which I work on since 2010 - it's more work than you'd think. We also eventually moved on and use a custom renderer to improve compatibility with the wide range of PDF files available and to offer a better performance than Apple's renderer, however not every use case might require this.