WKWebView: jquery datatable CSV export

Question

In my iOS app I'm using a WKWebView to display a jquery datatable with CSV button to export data (a page very similar to https://datatables.net/extensions/buttons/examples/initialisation/export.html). Now, when I tap on CSV button I would handle data to show it at the user, by QLPreviewController for example. On iOS Safari browser, when tap on CSV button, another tab is opened with data. In my WkWebView nothing happens.

Is there anybody who can help me to achieve my goal?

Answer 1

I solved by myself. I'm able to handle the tap by optional func webView(_ webView: WKWebView, createWebViewWith configuration: WKWebViewConfiguration, for navigationAction: WKNavigationAction, windowFeatures: WKWindowFeatures) -> WKWebView? method of WKUIDelegate

EDIT - Added code as requested by @SeriousSam in comment

// MARK: - WKUIDelegate

func webView(_ webView: WKWebView, createWebViewWith configuration: WKWebViewConfiguration, for navigationAction: WKNavigationAction, windowFeatures: WKWindowFeatures) -> WKWebView? {
    if navigationAction.targetFrame == nil {
       var urlString = navigationAction.request.url
       let lastPathComponent = urlString!.lastPathComponent
       let encodedLastPathComponent = lastPathComponent.addingPercentEncoding(withAllowedCharacters: .alphanumerics)
       urlString?.deleteLastPathComponent()
       let encodedUrl = urlString!.absoluteString+encodedLastPathComponent!
       let jsHandler = "var xhr = new XMLHttpRequest;xhr.responseType = 'blob';xhr.onload = function() {var recoveredBlob = xhr.response;var reader = new FileReader;reader.onload = function() {var blobAsDataUrl = reader.result;window.location = blobAsDataUrl;};reader.readAsDataURL(recoveredBlob);};xhr.open('GET', '\(encodedUrl)');xhr.setRequestHeader(\"Cache-Control\", \"no-store\");xhr.send();"
       webView.evaluateJavaScript(jsHandler, completionHandler: nil)
    }
    return nil
}

func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
    if let url = navigationAction.request.url {
        if (url.absoluteString.hasPrefix("data:")) {
            let splitted = url.absoluteString.components(separatedBy: "base64,")
            if splitted.count == 2 {
                if splitted[0].contains("csv") {
                    self.documentName = "export.csv"
                }
                if let data = Data(base64Encoded: splitted[1]), let documentName = self.documentName {
                    let fileName = String(format: "%@.%@", ProcessInfo.processInfo.globallyUniqueString, "\((documentName as NSString).pathExtension)")
                    let fileURL = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(fileName)
                    do {
                        try data.write(to: fileURL, options: .atomicWrite)
                        // show the CSV document ...
                        decisionHandler(.cancel)
                        return
                    } catch {
                        let alert = UIAlertController(title: NSLocalizedString("Errore", comment: "Error Alert Title"), message: error.localizedDescription, preferredStyle: .alert)
                        alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: nil))
                        self.present(alert, animated: true, completion: nil)
                        decisionHandler(.cancel)
                        return
                    }
                }
            }
        }
    }
    decisionHandler(.allow)
}