Question

从网址加载HTML5页面时我在该页面的某处获取了pdf，我必须下载该pdf或将其保存为base64。

这是pdf在HTML代码中的位置。我不能简单地点击“src”网址并获取pdf。

< embed width="100%" height="100%" name="plugin" id="plugin" src="https://myurl.com/fileToOpen.pdf” type="application/pdf" internalinstanceid="8" title="">

任何可以帮助我获取base64字符串或任何其他方法的JS？

Answer 1

<强>更新

来自他们所说的Docs

Fetch API提供了一个获取资源的接口（包括整个网络）。任何使用过的人都会觉得很熟悉的XMLHttpRequest

您还可以使用以下字符串从WKWebview

获取base64字符串

 let s = "path = document.getElementById(\"plugin\").src\n" +
        "\n" +
        "fetch(path).then(function (response) {\n" +
        " response.body.getReader().read().then(function(result) {\n" +
        " return btoa(String.fromCharCode.apply(null, result.value));\n" +
        " }).then(function(b64) {\n" +
        " window.webkit.messageHandlers.myInterface.postMessage(b64);\n" +
        " });\n" +
        "});"

fetch和xmlhttp都工作异步..所有你需要做的就是等待处理完成后使用javascript的桥接器将其传递给Swift（WKScriptMessageHandler）

使用以下代码从javascript到Swift 获取base64字符串。当base64字符串准备好被使用时，我正在使用WKScriptMessageHandler从Javascript 获取回调。在String中，您只需要传递pdf的url，它将执行ajax请求以获取pdf文件，然后将其转换为base64字符串。

import UIKit
import WebKit
class ViewController: UIViewController {
    @IBOutlet weak var btnPDF: UIButton!
    @IBOutlet weak var webViewParentView: UIView!
    var activityIndicator: UIActivityIndicatorView?
    var webView: WKWebView!
    @objc func didSelect(_ sender: UIView){
        let s="var xhr = new XMLHttpRequest();\n" +
            "xhr.open(\'GET\', \"https://codingexceptions.com/wkwebview/dummy.pdf\", true);\n" +
            "\n" +
            "xhr.responseType = \'arraybuffer\';\n" +
            "\n" +
            "xhr.onload = function(e) {\n" +
            " if (this.status == 200) {\n" +
            " var uInt8Array = new Uint8Array(this.response);\n" +
            " var i = uInt8Array.length;\n" +
            " var binaryString = new Array(i);\n" +
            " while (i--)\n" +
            " {\n" +
            " binaryString[i] = String.fromCharCode(uInt8Array[i]);\n" +
            " }\n" +
            " var data = binaryString.join(\'\');\n" +
            "\n" +
            " var base64 = window.btoa(data);\n" +
            "\n" +
            "window.webkit.messageHandlers.myInterface.postMessage(base64);" +
            "\n" +
            " }\n" +
            "};\n" +
            "\n" +
        "xhr.send();\n"
        webView.configuration.userContentController.add(self, name: "myInterface")
        webView?.evaluateJavaScript(s, completionHandler: {(string,error) in
            print(error ?? "no error")
        })
    }
    func setupWebView(){
        webView = WKWebView.init(frame: CGRect(x: 0, y: 0, width: webViewParentView.frame.width, height: webViewParentView.frame.height))
        webView.navigationDelegate = self
        webViewParentView.addSubview(webView)
        activityIndicator = UIActivityIndicatorView(activityIndicatorStyle: .gray)
        activityIndicator?.center = self.view.center
        self.view.addSubview(activityIndicator!)
        webView.load(URLRequest(url: URL(string: "https://codingexceptions.com/wkwebview/index.php")!))
        activityIndicator?.startAnimating()
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        btnPDF.addTarget(self, action: #selector(self.didSelect(_:)), for: .touchUpInside)

    }
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
         setupWebView()
    }
}
extension ViewController: WKScriptMessageHandler{
    func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
         print("Message received: \(message.name) with body: \(message.body)")
    }
}
extension ViewController: WKNavigationDelegate{
    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        self.activityIndicator?.stopAnimating()
        self.activityIndicator?.removeFromSuperview()
        self.activityIndicator = nil
    }
}

更新：从@Tarun的回答中指出来自embed标签的源

将行放在字符串变量s 的开头，然后在xhr.open中传递url

var url = document.getElementById("plugin").src

Answer 2

PS：使用答案作为评论，因为我需要格式化

您应该在webview中执行以下JavaScript

path = document.getElementById("plugin").src

fetch(path).then(function (response) {
    response.body.getReader().read().then(function(result) {
        return btoa(String.fromCharCode.apply(null, result.value));
    }).then(function(b64) {
        window.pdf_data = b64;
    });
});

然后你可以执行另一个查询来访问window.pdf_data，假设从javascript执行中获取返回值是可能的吗？

Answer 3

这个问题有时又被问到，但是，如果有人用 WKWebView 寻找快速解决方案来下载.pdf或文件管理器上的任何文件，这就是我的最终目的

class WebPortalVC: UIViewController, WKNavigationDelegate,WKUIDelegate, UIDocumentInteractionControllerDelegate,URLSessionDownloadDelegate {

覆盖以下函数，该函数将拦截url，在本例中，我们检查以.pdf和.csv结尾的ulr，并使用文件管理器视图重定向到open以打开。可以查看文件，下载并保存在设备存储中，空投或与其他应用共享

只需添加以下功能并检查。

 func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
    if let url = navigationAction.request.url {

        print("fileDownload: check ::  \(url)")

        let extention = "\(url)".suffix(4)

        if extention == ".pdf" ||  extention == ".csv"{
            print("fileDownload: redirect to download events. \(extention)")
            DispatchQueue.main.async {
                self.downloadPDF(tempUrl: "\(url)")
            }
            decisionHandler(.cancel)
            return
        }

    }

    decisionHandler(.allow)
}

func downloadPDF(tempUrl:String){
    print("fileDownload: downloadPDF")
    guard let url = URL(string: tempUrl) else { return }
    let urlSession = URLSession(configuration: .default, delegate: self, delegateQueue: OperationQueue())
    let downloadTask = urlSession.downloadTask(with: url)
    downloadTask.resume()
    //showHUD(isShowBackground: true); //show progress if you need
}
func documentInteractionControllerViewControllerForPreview(_ controller: UIDocumentInteractionController) -> UIViewController {
    print("fileDownload: documentInteractionControllerViewControllerForPreview")
    return self
}
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
    // create destination URL with the original pdf name
    print("fileDownload: urlSession")
    guard let url = downloadTask.originalRequest?.url else { return }
    print("fileDownload: urlSession \(url)")
    let documentsPath = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
    let destinationURL = documentsPath.appendingPathComponent(url.lastPathComponent)
    // delete original copy
    try? FileManager.default.removeItem(at: destinationURL)
    // copy from temp to Document
    do {
        try FileManager.default.copyItem(at: location, to: destinationURL)
        myViewDocumentsmethod(PdfUrl:destinationURL)
        print("fileDownload: downloadLocation", destinationURL)
        DispatchQueue.main.async {
            NBMaterialToast.showWithText(self.view, text: "Download Completed", duration: NBLunchDuration.long)
        }
    } catch let error {
        print("fileDownload: error \(error.localizedDescription)")
    }
   // dismissHUD(isAnimated: false); //dismiss progress
}
func myViewDocumentsmethod(PdfUrl:URL){
    print("fileDownload: myViewDocumentsmethod \(PdfUrl)")
    DispatchQueue.main.async {
        let controladorDoc = UIDocumentInteractionController(url: PdfUrl)
        controladorDoc.delegate = self
        controladorDoc.presentPreview(animated: true)
    }
}

Answer 4

您是要将PDF下载到iPhone还是Mac？通常，无法将PDF直接下载到iPhone，因为iPhone本身无法存储PDF。您需要拥有iBooks或iCloud Drive，然后在另一个窗口中打开PDF，然后手动下载。在下载PDF之前仍需要进行用户交互，这意味着用户必须批准下载。通过将JavaScript注入WKWebView实例直接下载是不可能的。

下载WKWebView

4 个答案:

fetch和xmlhttp都工作异步..所有你需要做的就是等待处理完成后使用javascript的桥接器将其传递给Swift（WKScriptMessageHandler）