[SWIFT] I made an app to scribble with PencilKit on a PDF file


Hello. My name is HAAAAAN. This time, as the title suggests, I made an app that allows you to scribble on a PDF file. I would like to write it with the meaning of memorization.

Since I am a beginner, I know that there may be incorrect expressions and understandings, but thank you for your understanding.

In addition, this app is just for scribbling, so There is no save function. (Future tasks)


MacOS Xcode swift iPad Pro(iOS:13.6)


I'll stay still

① Display the PDF file on the screen ② You can scribble on the displayed PDF file

I'll do it soon

① When the scribble is finished, save the PDF file with the scribble ② When ① is completed, convert the image file to a PDF file -As an image, it feels like taking a screenshot of the screen and converting the image to PDF. (I don't know if it can be done)


--Open the storyboard and add one View to the original view controller. --Set PDFView to Class name of CustomClass of the added View and make an Outlet connection. --Add the PDF file you want to display to the project file.



import UIKit
import PDFKit
import PencilKit

class ViewController: UIViewController{
    @IBOutlet weak var pdfView: PDFView!
    override func viewDidLoad() {
        // Do any additional setup after loading the view.
        if let sourceURL = Bundle.main.url(forResource: "Test", withExtension: "pdf") {
            if let source = PDFDocument(url: sourceURL) {
                pdfView.document = source //PDF URL
                pdfView.autoScales = true //PDF fits on screen
                pdfView.displayMode = .singlePage //1 page display

        let canvas = PKCanvasView(frame: view.frame) //Drawing area settings
        view.addSubview(canvas) //Add drawing area above PDF
        canvas.tool = PKInkingTool(.pen, color: .black, width: 15) //Pen settings
        canvas.isOpaque = false //Make the background transparent(Okay)

        if let window = UIApplication.shared.windows.first {
            if let toolPicker = PKToolPicker.shared(for: window) {
                toolPicker.setVisible(true, forFirstResponder: canvas)

Clogged up

・ When implementing View As a configuration, put PDFView on the original view controller and put it on it I was thinking of putting a View for drawing, and I was able to implement it exactly as it was. In an article somewhere while wandering the Web, the screen goes black when drawing with a pen There was a thing that I encountered a problem, and I had the exact same symptom on the way.

Probably some processing is moving by the trigger at the time of gesture, I think When I changed the background color, the screen that should be black became the color set as the background color. I decided to make the View itself transparent.

At first, I set the alpha value for the background color of the View for drawing, but I stopped it By setting the isOpaque value of View to false, the problem at the time of gesture has disappeared.


- [Swift] Display PDF with PDFKit - Introducing PencilKit with just 3 lines of code to support Apple Pencil - [Swift] How to use isOpaque to make windows transparent

This time I just combined the above articles! (Don!!!)

Later talk

PDF Annotation is one of the features of PDFKit without installing PencilKit There is a function called (annotation function), which means that it can be drawn directly on the PDF ... It seems that you can save the trouble of capturing from an Image file to a PDF file, so I wonder if I can implement it using that.

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