Printing contents of WKWebView (OS X)

Question

I am trying to print the contents of a WkWebView, but when the print panel appears the print preview is empty.

Here is the code:

- (void)viewDidLoad {
    [super viewDidLoad];

    WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];
    _webView = [[WKWebView alloc] initWithFrame:self.webViewOutlet.frame configuration:config];
    [_webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"https://www.google.com"]]];
    [_webViewOutlet addSubview:_webView];
    _webView.navigationDelegate = self;

}

I have an outlet for the WKWebView so I can see if it is loaded and I am putting the print call into the didFinishNavigation delegate method like this just to be sure:

- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation
{
    [self.webView print:nil];
}

No matter what page do, the print preview is always a blank page. I also tried using NSPrintOperations and the results were the same – print previews and saved PDFs were blank pages.

Any ideas what I am doing wrong? Is there another way to print/convert WKWebView to PDF? Suggestions are welcome. Thank You.

Answer 1

At long last, it seems Apple has done something about this in Swift. As of iOS 14 and macOS 11, you can use createPDF on a WKWebView to save the contents of your HTML file to a PDF.

https://developer.apple.com/documentation/webkit/wkwebview/3650490-createpdf

I just tried it in a Mac app (Xcode 13 on macOS 11.6), and it worked.

Here's a basic example:

func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
   
  webView.createPDF(){ result in
    switch result{
      case .success(let data):
        //Save the returned data to a PDF file
        try! data.write(to: URL(fileURLWithPath: "\(folder)/Cool.pdf"))

      case .failure(let error):
        print(error)
    }
  }
}

Answer 2

If your app can require macOS 10.13 or later, there is a new method on WKWebView: takeSnapshot(with:completionHandler:), which generates an NSImage representation of your web view.

As far as I know this is the best option for rendering a WKWebView to image.