How to view DJVU file in UIWebview

I am having iOS application in which I want to view data from .djvu file. Is there any way to read .djvu file in Swift or inside UIWebview.

I have also tried following solutions to view djvu file in uiwebview but that doesn't help.

1. Directly open djvu file in uiwebview

 let urlPage : URL! = URL(string: "http://192.168.13.5:13/myData/5451890-OP.djvu")        
 webView.loadRequest(URLRequest(url: urlPage))

2. Secondly i have tried to convert djvu file to pdf and the showing that converted pdf file into view. Reference link: https://github.com/MadhuriMane/ios-djvu-reader But that gives mirror image with low quality.

3. I have tried to preview file with the help of UIDocumentInteractionController() and it's delegate method but didn't work.

Please suggest any possible ways to do so.

Solution

Keeping in mind that .djvu files are less popular then similar formats like EPUB, MOBI, PDF and other eBook file formats, I would have following approach to workaround the problem.

1) Create a Web Service to convert djvu files to pdf ex.: http://example.com/djvuToPdf/djvuFile/outputFile

2) Read the PDF file in UIWebView

To create a Web Service I would assume that you have access to any Linux distributed Server, in my case Ubuntu 16.04.

Step one: Install djvulibre sudo apt-get install djvulibre-bin ghostscript

Step two: test run $ djvups inputFile.djvu | ps2pdf - outputFile.pdf. You may also use the ddjvu command. However, files converted with ddjvu command are 10x larger than djvups command. You would want to consider to use --help the explore the settings like mode, quality and so on.

Step three: Creating a Web Service (to keep things simple, I use PHP, use anything at your convenience [Python golang])

<?php

$inputFile = $_GET['input_file'];
$outputFile = $_GET['output_file'];

// use shell exec to execute the command
// keep in mind that the conversion takes quite a long time
shell_exec(sprintf("djvups %s | ps2pdf - %s", $inputFile, $outputFile));

$name = $outputFile;
//file_get_contents is standard function
$content = file_get_contents($name);
header('Content-Type: application/pdf');
header('Content-Length: '.strlen( $content ));
header('Content-disposition: inline; filename="' . $name . '"');
header('Cache-Control: public, must-revalidate, max-age=0');
header('Pragma: public');
header('Expires: Sat, 26 Jul 1997 05:00:00 GMT');
header('Last-Modified: '.gmdate('D, d M Y H:i:s').' GMT');
echo $content;


?>

Final Step: load PDF in App

As Apple advise, consider using WKWebView in place of UIWebView.

if let pdfURL = Bundle.main.url(forResource: "pdfFile", withExtension: "pdf", subdirectory: nil, localization: nil)  {
    do {
        let data = try Data(contentsOf: pdfURL)
        let webView = WKWebView(frame: CGRect(x:20,y:20,width:view.frame.size.width-40, height:view.frame.size.height-40))
        webView.load(data, mimeType: "application/pdf", characterEncodingName:"", baseURL: pdfURL.deletingLastPathComponent())
        view.addSubview(webView)

    }
    catch {
        // catch errors here
    }

}