UIImage extension for PDF documents

UIImage+PDFDocument.swift

import UIKit

extension UIImage {
    convenience init?(pdfDocument: CGPDFDocument, pageNumber: Int = 1) {
        guard let page = pdfDocument.page(at: pageNumber) else { return nil }
        let size = page.getBoxRect(.mediaBox).size
        
        UIGraphicsBeginImageContextWithOptions(size, true, UIScreen.main.scale)
        let context = UIGraphicsGetCurrentContext()!
        context.saveGState()
        context.translateBy(x: 0.0, y: size.height)
        context.scaleBy(x: 1.0, y: -1.0)
        context.concatenate(page.getDrawingTransform(.mediaBox, rect: CGRect(origin: .zero, size: size), rotate: 0, preserveAspectRatio: true))
        context.drawPDFPage(page)
        context.restoreGState()
        let pdfImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()
        
        guard let cgImage = pdfImage.cgImage else { return nil }
        self.init(cgImage: cgImage)
    }
}