Convert SwiftUI View to PDF on iOS

Question

I was drawing some nice graphs with SwiftUI, because it is so simple and easy to do. Then I wanted to export the whole SwiftUI View to a PDF such that someone else can view the graphs in a nice way. SwiftUI does not offer a solution for this directly.

Cheers,
Alex

Answer 1

After some thinking I came up with the idea of combining the UIKit to PDF method and SwiftUI.

At first you create your SwiftUI view, then you put into an UIHostingController. You render the HostingController on a window behind all other views and and draw its layer on a PDF. Sample code is listed below.

func exportToPDF() {

    let documentDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
    let outputFileURL = documentDirectory.appendingPathComponent("SwiftUI.pdf")

    //Normal with
    let width: CGFloat = 8.5 * 72.0
    //Estimate the height of your view
    let height: CGFloat = 1000
    let charts = ChartsView()

    let pdfVC = UIHostingController(rootView: charts)
    pdfVC.view.frame = CGRect(x: 0, y: 0, width: width, height: height)

    //Render the view behind all other views
    let rootVC = UIApplication.shared.windows.first?.rootViewController
    rootVC?.addChild(pdfVC)
    rootVC?.view.insertSubview(pdfVC.view, at: 0)

    //Render the PDF
    let pdfRenderer = UIGraphicsPDFRenderer(bounds: CGRect(x: 0, y: 0, width: 8.5 * 72.0, height: height))

    do {
        try pdfRenderer.writePDF(to: outputFileURL, withActions: { (context) in
            context.beginPage()
            pdfVC.view.layer.render(in: context.cgContext)
        })

        self.exportURL = outputFileURL
        self.showExportSheet = true

    }catch {
        self.showError = true
        print("Could not create PDF file: \(error)")
    }

    pdfVC.removeFromParent()
    pdfVC.view.removeFromSuperview()
}

Answer 2

I loved this answer, but couldn't get it to work. I was getting an exception and the catch wasn't being executed.

After some head scratching, and writing up a SO Question asking how to debug it (which I never submitted), I realized that the solution, while not obvious, was simple: wrap the rendering phase in an async call to the main queue:

//Render the PDF

 let pdfRenderer = UIGraphicsPDFRenderer(bounds: CGRect(x: 0, y: 0, width: 8.5 * 72.0, height: height))
 DispatchQueue.main.async {
     do {
         try pdfRenderer.writePDF(to: outputFileURL, withActions: { (context) in
             context.beginPage()
             pdfVC.view.layer.render(in: context.cgContext)
         })
         print("wrote file to: \(outputFileURL.path)")
     } catch {
         print("Could not create PDF file: \(error.localizedDescription)")
     }
 }

Thanks, SnOwfreeze!

Answer 3

I tried all the answers, but they didn't work for me (Xcode 12.4, iOS 14.4). Here is what's worked for me:

import SwiftUI

func exportToPDF() {
    let outputFileURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.appendingPathComponent("SwiftUI.pdf")
    let pageSize = CGSize(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height)
    
    //View to render on PDF
    let myUIHostingController = UIHostingController(rootView: ContentView())
    myUIHostingController.view.frame = CGRect(origin: .zero, size: pageSize)
    
    
    //Render the view behind all other views
    guard let rootVC = UIApplication.shared.windows.first?.rootViewController else {
        print("ERROR: Could not find root ViewController.")
        return
    }
    rootVC.addChild(myUIHostingController)
    //at: 0 -> draws behind all other views
    //at: UIApplication.shared.windows.count -> draw in front
    rootVC.view.insertSubview(myUIHostingController.view, at: 0)
    
    
    //Render the PDF
    let pdfRenderer = UIGraphicsPDFRenderer(bounds: CGRect(origin: .zero, size: pageSize))
    DispatchQueue.main.async {
        do {
            try pdfRenderer.writePDF(to: outputFileURL, withActions: { (context) in
                context.beginPage()
                myUIHostingController.view.layer.render(in: context.cgContext)
            })
            print("wrote file to: \(outputFileURL.path)")
        } catch {
            print("Could not create PDF file: \(error.localizedDescription)")
        }
        
        //Remove rendered view
        myUIHostingController.removeFromParent()
        myUIHostingController.view.removeFromSuperview()
    }
}

Note: Don't try to use this function in a view with .onAppear when you try to export the same view. This will result in a endless loop naturally.