如何处理 WKWebView 中的 blob url 并下载文件？

Question

我需要在 WKWebView 中实现文件下载。

我的示例实现：

@available(iOS 14.5, *)
func webView(_ webView: WKWebView, navigationResponse: WKNavigationResponse, didBecome download: WKDownload) {
    download.delegate = self
}
@available(iOS 14.5, *)
func webView(_ webView: WKWebView, navigationAction: WKNavigationAction, didBecome download: WKDownload) {
    download.delegate = self
}
func webView(_ webView: WKWebView, decidePolicyFor navigationResponse: WKNavigationResponse, decisionHandler: @escaping (WKNavigationResponsePolicy) -> Void) {
    if let mimeType = navigationResponse.response.mimeType {
        if let url = navigationResponse.response.url {
            if #available(iOS 14.5, *) {
                decisionHandler(.download)
            } else {
                let ext = getExtension(mimeType)
                let fileName = "file." + ext;
                downloadData(fromURL: url, fileName: fileName) { success, destinationURL in
                    if success, let destinationURL = destinationURL {
                        self.openDownloadFile(destinationURL)
                    }
                }
                decisionHandler(.cancel)
            }
            return
        }
    }
    decisionHandler(.allow)
}

private func downloadData(fromURL url: URL,
                          fileName: String,
                          completion: @escaping (Bool, URL?) -> Void) {
    webView.configuration.websiteDataStore.httpCookieStore.getAllCookies { cookies in
        let session = URLSession.shared
        session.configuration.httpCookieStorage?.setCookies(cookies, for: url, mainDocumentURL: nil)
        let task = session.downloadTask(with: downloadURL) { localURL, _, error in
            if let localURL = localURL {
                let destinationURL = self.moveDownloadedFile(url: localURL, fileName: fileName)
                completion(true, destinationURL)
            } else {
                completion(false, nil)
            }
        }
        task.resume()
    }
}

private func moveDownloadedFile(url: URL, fileName: String) -> URL {
    let tempDir = NSTemporaryDirectory()
    let destinationPath = tempDir + fileName
    let destinationURL = URL(fileURLWithPath: destinationPath)
    try? FileManager.default.removeItem(at: destinationURL)
    try? FileManager.default.moveItem(at: url, to: destinationURL)
    return destinationURL
}

private func openDownloadFile(_ fileUrl: URL) {
    DispatchQueue.main.async {
        let controller = UIActivityViewController(activityItems: [fileUrl], applicationActivities: nil)
        controller.popoverPresentationController?.sourceView = self.view
        controller.popoverPresentationController?.sourceRect = self.view.frame
        controller.popoverPresentationController?.barButtonItem = self.navigationItem.rightBarButtonItem
        self.present(controller, animated: true, completion: nil)
    }
}

它适用于 iOS >= 14.5 并且当响应是文件时。 但是当 url 是 blob（例如 "blob:http://example.com/bd0ae6c8-796c-488e-b691-cee86fa72f04"）时，它不适用于 iOS

返回不支持的 URL 错误。

我尝试像在 android (Example for android) 中一样处理和下载 blob url：

private func downloadBlobFile(blobUrl: String, fileName: String, mimeType: String) {
    webView.evaluateJavaScript("javascript: var xhr = new XMLHttpRequest();" +
        "xhr.open('GET', '" + blobUrl + "', true);" +
        "xhr.setRequestHeader('Content-type','" + mimeType + "');" +
        "xhr.responseType = 'blob';" +
        "xhr.onload = function(e) {" +
        "    if (this.status == 200) {" +
        "        var blob = this.response;" +
        "        var reader = new FileReader();" +
        "        reader.readAsDataURL(blob);" +
        "        reader.onloadend = function() {" +
        "            base64data = reader.result;" +
        "            window.webkit.messageHandlers.callback.postMessage(base64data);" +
        "        }" +
        "    }" +
        "};" +
        "xhr.send();")
}

此代码在 Android 上运行良好，但在 iOS 上 xhr.onload 未调用。 它调用xhr.onerror，状态为0，responseText为空。

我还尝试从 blob url 中删除“blob:”。 "blob:http://example.com/bd0ae6c8-796c-488e-b691-cee86fa72f04" -> "http://example.com/bd0ae6c8-796c-488e-b691-cee86fa72f04" 并使用 URLSession 下载它。但它让我损坏了文件。

我尝试添加 LSApplicationQueriesSchemes blob，但它对我没有帮助。

Answer 1

也许您应该在孤立的世界中评估 JavaScript。对于 iOS，您应该评估 defauliClientWorld 中的 js 代码。