Not getting a right resolution of the page of PDF in iOS

Question

I want to know the resolution of the page of PDF. I have tried one solution but getting the wrong resolution (612 x 792). But a correct resolution is 816x1056.

guard let provider = CGDataProvider(data: fileData as CFData) else { return }
guard let coreDocument = CGPDFDocument(provider) else { return }
guard let page = coreDocument.page(at: 0) else { return }

let size = page.getBoxRect(.mediaBox).size

Answer 1

The "resolution" you are looking for is given in px (= ¹/₉₆ in) while the dimensions in PDFs are given in pt (= ¹/₇₂ in).

Thus, you can calculate your desired output by multiplying the dimensions from the PDF by ⁴/₃.

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Some asides...

Strictly speaking PDF pages don't have "resolutions" as such because PDF is a vector format. Of course, though, their pages have dimensions which is what you are determining.

Furthermore, you indeed should first look for the CropBox and only in its absence use the MediatBox. You can read about all the defined boxes here.