PDF Page View

A UIView subclass to display PDF pages

Usage

Copy the PDFPageView.swift source file from the demo app into your Xcode project.
On your Storyboard, add a UIView to one of your view controllers and set the class to PDFPageView.
- Turn off the Opaque property.
- Set the Content Mode property appropriately. (Aspect Fit is recommended.)
- Set the Use Crop Box property appropriately, depending on whether your PDF expects cropping.
  NOTE: Content Mode always positions the content using the crop box, not the media box.
- Don't forget your layout constraints!

...or do the equivalent in your view controller's loadView() code.

In your view controller's viewDidLoad(), set the page view's .page property to the PDFPage you want to display.
- You need to import PDFKit at the top of your source file.
- You need to load your PDF file as a PDFDocument object.

Download the entire Xcode project.
Build and run for the Simulator. (Or a real device, if you add your developer license to the project.)
The demo app hosts the PDFPageView in a UIPageViewController, so swipe left and right to turn pages.

I'd use a layer hierarchy instead of doing everything directly in the view.

Create a CALayer to hold the PDF content.
Flip its geometry to match the PDF.
Set the bounds of the layer using the size of the media box and the origin of the crop box.
Use the .position and .anchorPoint of the layer to implement content gravity, rather than transforms.
Only use a scaling transform for the Aspect Fill, Aspect Fit, and Size to Fit content modes.