Playground showing how to convert a base 64 encoded PDF to an UIImage.

PDFBase64ToImageViewController.swift

//
//  PDFBase64ToImageViewController.swift
//
//  Created by Felix Mau on 20.04.21.
//  Copyright © 2021 Felix Mau. All rights reserved.
//

import PlaygroundSupport
import UIKit
import PDFKit

/// Icons made by [Freepik](https://www.freepik.com) from [Flaticon](https://www.flaticon.com/).
/// Direct URL <https://www.flaticon.com/free-icon/settings_675579>.
let pdfAsBase64 = "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"

class PDFBase64ToImageViewController: UIViewController {

    // MARK: - Config

    private enum Config {
        static let imageSize: CGFloat = 320
    }

    // MARK: - Private methods

    override func loadView() {
        let view = UIView()
        view.backgroundColor = .clear

        // See extension on `String` below for the implementation.
        let image = pdfAsBase64.convertPDFBase64StringToImage()

        let imageView = UIImageView(image: image)
        imageView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(imageView)

        NSLayoutConstraint.activate([
            imageView.widthAnchor.constraint(equalToConstant: Config.imageSize),
            imageView.heightAnchor.constraint(equalToConstant: Config.imageSize),

            imageView.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            imageView.centerYAnchor.constraint(equalTo: view.centerYAnchor),
        ])

        self.view = view
    }
}

extension String {

    /// Based on
    /// [Convert a PDF to an Image in Swift](https://pspdfkit.com/blog/2020/convert-pdf-to-image-in-swift/)
    func convertPDFBase64StringToImage() -> UIImage? {
        guard
            let imageData = Data(base64Encoded: self, options: .ignoreUnknownCharacters),
            let document = PDFDocument(data: imageData),
            let page = document.page(at: 0)
        else {
            return nil
        }

        // Fetch the page rect for the page we want to render.
        let pageRect = page.bounds(for: .mediaBox)

        let renderer = UIGraphicsImageRenderer(size: pageRect.size)
        return renderer.image { ctx in
            // Translate the context so that we only draw the `cropRect`.
            ctx.cgContext.translateBy(x: -pageRect.origin.x,
                                      y: pageRect.size.height - pageRect.origin.y)

            // Flip the context vertically because the Core Graphics coordinate system starts from the bottom.
            ctx.cgContext.scaleBy(x: 1, y: -1)

            // Draw the PDF page.
            page.draw(with: .mediaBox, to: ctx.cgContext)
        }
    }
}

// Present the view controller in the Live View window
PlaygroundPage.current.liveView = PDFBase64ToImageViewController()