打开pdf，ppt ..等文件时，如何使用swift语言在Xcode中添加关闭或后退按钮？
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【中文标题】打开pdf，ppt ..等文件时，如何使用swift语言在Xcode中添加关闭或后退按钮？【英文标题】：How to add close or back button in Xcode using swift language when a file such as pdf, ppt .. etc. is opened? 【发布时间】：2020-11-21 14:30:10 【问题描述】：首先，我是 Swift 和 Objective C 语言的新手。我的问题是我有一个使用 swift 语言的 ios 设备 WebView 应用程序，该应用程序在打开 pdf、ppt 等文档文件时使用。没有关闭文件或返回上一个选项的选项。刚刚搜索了这个问题，并在下面的链接中找到了目标 c 的解决方案，但我的问题是我使用的是 swift 而不是目标 c。xCode add close/done button when pdf file is opened 我的代码是：
import UIKit
import WebKit
import QuickLook
import AVFoundation
ViewController 类：UIViewController、WKUIDelegate、WKNavigationDelegate、QLPreviewControllerDataSource、WKScriptMessageHandler
var documentPreviewController = QLPreviewController()
var documentUrl = URL(fileURLWithPath: "")
let webViewConfiguration = WKWebViewConfiguration()
let userContentController = WKUserContentController()
var webViewCookieStore: WKHTTPCookieStore!
var webView: WKWebView!
override func loadView()
let webConfiguration = WKWebViewConfiguration()
webView = WKWebView(frame: .zero, configuration: webConfiguration)
webView.uiDelegate = self
view = webView
override func viewDidLoad()
super.viewDidLoad()
// initial configuration of custom javascripts
webViewConfiguration.userContentController = userContentController
webViewConfiguration.websiteDataStore = WKWebsiteDataStore.default()
// init this view controller to receive JavaScript callbacks
userContentController.add(self, name: "openDocument")
userContentController.add(self, name: "jsError")
// QuickLook document preview
documentPreviewController.dataSource = self
// link the appDelegate to be able to receive the deviceToken
//------------
// Add script message handlers that, when run, will make the function
// window.webkit.messageHandlers.test.postMessage() available in all frames.
// controller.add(self, name: "test")
guard let scriptPath = Bundle.main.path(forResource: "script", ofType: "js"),
let scriptSource1 = try? String(contentsOfFile: scriptPath) else return
let userScript = WKUserScript(source: scriptSource1, injectionTime: .atDocumentEnd, forMainFrameOnly: true)
userContentController.addUserScript(userScript)
//----- end
webView = WKWebView(frame: CGRect.zero, configuration: webViewConfiguration)
let myURL = URL(string:"My URL")
let myRequest = URLRequest(url: myURL!)
// see "The 2 delegates": // https://samwize.com/2016/06/08/complete-guide-to-implementing-wkwebview/
webView.uiDelegate = self
webView.navigationDelegate = self
view.addSubview(webView)
let layoutGuide = view.safeAreaLayoutGuide
webView.translatesAutoresizingMaskIntoConstraints = false
webView.leadingAnchor.constraint(equalTo: layoutGuide.leadingAnchor).isActive = true
webView.trailingAnchor.constraint(equalTo: layoutGuide.trailingAnchor).isActive = true
webView.topAnchor.constraint(equalTo: layoutGuide.topAnchor).isActive = true
webView.bottomAnchor.constraint(equalTo: layoutGuide.bottomAnchor).isActive = true
self.load(myRequest)
webViewCookieStore = webView.configuration.websiteDataStore.httpCookieStore
webView.allowsBackForwardNavigationGestures = true
if(webView.canGoBack)
//Go back in webview history
webView.goBack()
else
//Pop view controller to preview view controller
self.navigationController?.popViewController(animated: true)
let cameraMediaType = AVMediaType.video
let cameraAuthorizationStatus = AVCaptureDevice.authorizationStatus(for: cameraMediaType)
switch cameraAuthorizationStatus
case .denied: break
case .authorized: break
case .restricted: break
case .notDetermined:
// Prompting user for the permission to use the camera.
AVCaptureDevice.requestAccess(for: cameraMediaType) granted in
if granted
print("Granted access to \(cameraMediaType)")
else
print("Denied access to \(cameraMediaType)")
@unknown default:
fatalError()
private func load(_ url: URL)
load(URLRequest(url:url))
private func load(_ req: URLRequest)
let request = req
// request.setValue(self.deviceToken, forHTTPHeaderField: "iosDeviceToken")
//request.setValue(self.myVersion as? String, forHTTPHeaderField: "iosVersion")
//request.setValue(self.myBuild as? String, forHTTPHeaderField: "iosBuild")
//request.setValue(UIDevice.current.modelName, forHTTPHeaderField: "iosModelName")
//debugPrintHeaderFields(of: request, withMessage: "Loading request")
webView.load(request)
debugPrint("Loaded request=\(request.url?.absoluteString ?? "n/a")")
func webView(_ webView: WKWebView,
decidePolicyFor navigationAction: WKNavigationAction,
decisionHandler: @escaping (WKNavigationActionPolicy) -> Void)
let url = navigationAction.request.url
if openInDocumentPreview(url!)
decisionHandler(.cancel)
executeDocumentDownloadScript(forAbsoluteUrl: url!.absoluteString)
else
decisionHandler(.allow)
/*
Handler method for JavaScript calls.
Receive JavaScript message with downloaded document
*/
public func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage)
debugPrint("did receive message \(message.name)")
if (message.name == "openDocument")
previewDocument(messageBody: message.body as! String)
else if (message.name == "jsError")
debugPrint(message.body as! String)
/*
Open downloaded document in QuickLook preview
*/
private func previewDocument(messageBody: String)
// messageBody is in the format ;data:;base64,
// split on the first ";", to reveal the filename
let filenameSplits = messageBody.split(separator: ";", maxSplits: 1, omittingEmptySubsequences: false)
let filename = String(filenameSplits[0])
// split the remaining part on the first ",", to reveal the base64 data
let dataSplits = filenameSplits[1].split(separator: ",", maxSplits: 1, omittingEmptySubsequences: false)
let data = Data(base64Encoded: String(dataSplits[1]))
if (data == nil)
debugPrint("Could not construct data from base64")
return
// store the file on disk (.removingPercentEncoding removes possible URL encoded characters like "%20" for blank)
let localFileURL = FileManager.default.temporaryDirectory.appendingPathComponent(filename.removingPercentEncoding ?? filename)
do
try data!.write(to: localFileURL);
catch
debugPrint(error)
return
// and display it in QL
DispatchQueue.main.async
self.documentUrl = localFileURL
self.documentPreviewController.refreshCurrentPreviewItem()
self.present(self.documentPreviewController, animated: true, completion: nil)
/*
Implementation for QLPreviewControllerDataSource
*/
func previewController(_ controller: QLPreviewController, previewItemAt index: Int) -> QLPreviewItem
return documentUrl as QLPreviewItem
/*
Implementation for QLPreviewControllerDataSource
We always have just one preview item
*/
func numberOfPreviewItems(in controller: QLPreviewController) -> Int
return 1
/*
Checks if the given url points to a document download url
*/
private func openInDocumentPreview(_ url : URL) -> Bool
// this is specific for our application - can be everything in your application
return url.absoluteString.contains("/APP/connector")
/*
Intercept the download of documents in webView, trigger the download in JavaScript and pass the binary file to JavaScript handler in Swift code
*/
private func executeDocumentDownloadScript(forAbsoluteUrl absoluteUrl : String)
// TODO: Add more supported mime-types for missing content-disposition headers
webView.evaluateJavaScript("""
(async function download()
const url = '\(absoluteUrl)';
try
// we use a second try block here to have more detailed error information
// because of the nature of JS the outer try-catch doesn't know anything where the error happended
let res;
try
res = await fetch(url,
credentials: 'include'
);
catch (err)
window.webkit.messageHandlers.jsError.postMessage(`fetch threw, error: $err, url: $url`);
return;
if (!res.ok)
window.webkit.messageHandlers.jsError.postMessage(`Response status was not ok, status: $res.status, url: $url`);
return;
const contentDisp = res.headers.get('content-disposition');
if (contentDisp)
const match = contentDisp.match(/(^;|)\\s*filename=\\s*(\"([^\"]*)\"|([^;\\s]*))\\s*(;|$)/i);
if (match)
filename = match[3] || match[4];
else
// TODO: we could here guess the filename from the mime-type (e.g. unnamed.pdf for pdfs, or unnamed.tiff for tiffs)
window.webkit.messageHandlers.jsError.postMessage(`content-disposition header could not be matched against regex, content-disposition: $contentDisp url: $url`);
else
window.webkit.messageHandlers.jsError.postMessage(`content-disposition header missing, url: $url`);
return;
if (!filename)
const contentType = res.headers.get('content-type');
if (contentType)
if (contentType.indexOf('application/json') === 0)
filename = 'unnamed.pdf';
else if (contentType.indexOf('image/tiff') === 0)
filename = 'unnamed.tiff';
if (!filename)
window.webkit.messageHandlers.jsError.postMessage(`Could not determine filename from content-disposition nor content-type, content-dispositon: $contentDispositon, content-type: $contentType, url: $url`);
let data;
try
data = await res.blob();
catch (err)
window.webkit.messageHandlers.jsError.postMessage(`res.blob() threw, error: $err, url: $url`);
return;
const fr = new FileReader();
fr.onload = () =>
window.webkit.messageHandlers.openDocument.postMessage(`$filename;$fr.result`)
;
fr.addEventListener('error', (err) =>
window.webkit.messageHandlers.jsError.postMessage(`FileReader threw, error: $err`)
)
fr.readAsDataURL(data);
catch (err)
// TODO: better log the error, currently only TypeError: Type error
window.webkit.messageHandlers.jsError.postMessage(`JSError while downloading document, url: $url, err: $err`)
)();
// null is needed here as this eval returns the last statement and we can't return a promise
null;
""") (result, err) in
if (err != nil)
debugPrint("JS ERR: \(String(describing: err))")
var toolbars: [UIView] = []
var observations : [NSKeyValueObservation] = []
override func viewWillAppear(_ animated: Bool)
super.viewWillAppear(animated)
navigationController?.toolbar.isHidden = false
if let navigationToobar = navigationController?.toolbar
let observation = navigationToobar.observe(\.isHidden) [weak self] (changedToolBar, change) in
if self?.navigationController?.toolbar.isHidden == true
self?.navigationController?.toolbar.isHidden = false
observations.append(observation)
toolbars = toolbarsInSubviews(forView: view)
for toolbar in toolbars
toolbar.isHidden = false
let observation = toolbar.observe(\.isHidden) (changedToolBar, change) in
if let isHidden = change.newValue,
isHidden == true
changedToolBar.isHidden = false
observations.append(observation)
override func viewDidAppear(_ animated: Bool)
super.viewDidAppear(false)
//This hides the share item
if let add = self.children.first as? UINavigationController
if let layoutContainerView = add.view.subviews[1] as? UINavigationBar
layoutContainerView.subviews[2].subviews[1].isHidden = false
private func toolbarsInSubviews(forView view: UIView) -> [UIView]
var toolbars: [UIView] = []
for subview in view.subviews
if subview is UIToolbar
toolbars.append(subview)
toolbars.append(contentsOf: toolbarsInSubviews(forView: subview))
return toolbars
【问题讨论】：
【参考方案1】：到目前为止，您做得非常出色。一个小的调整将修复您的代码。回调需要在与实际回调匹配的方法中
func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!)
将canGoBack代码移动如下：
func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!)
if webView.canGoBack
let backButton = UIBarButtonItem(title: "Back", style: .plain, target: self, action: #selector(backButtonPressed))
navigationItem.rightBarButtonItem = backButton
else
self.navigationItem.rightBarButtonItem = nil
它调用的方法可能如下所示（基于您提供的链接）：
@objc
func backButtonPressed()
if webView.canGoBack
webView.goBack()
else
self.navigationController?.popViewController(animated: true)
编辑：（这是将控制器嵌入 UINavigationController 的方法）
我假设您正在使用 Interface Builder。 （我不会这样做，但它应该适合你）。
点击 LaunchScreen.storyboard（在左侧栏中）
单击并展开 View Controller Scene（顶部右侧的下一列）
点击视图控制器
移动到屏幕顶部并从菜单中选择：
/Editor/Embed In/Navigation Controller
这应该就是您需要做的所有事情。但是查看导航控制器并了解它们如何工作/为什么以及何时需要它们。 它们非常强大，正如您所了解的，它们是必不可少的！ ?
【讨论】：
感谢您的回复，代码看起来不错，但不幸的是，当打开文件时，看不到返回按钮。 您是否将此视图控制器放置在 UINavigationController 中？您的代码没有显示，它是必需的。 刚刚我已经放在那里，但仍然没有显示后退按钮。请问，您能否将您预定义的代码块添加到我上面发布的代码片段中？以上是关于打开pdf，ppt ..等文件时，如何使用swift语言在Xcode中添加关闭或后退按钮？的主要内容，如果未能解决你的问题，请参考以下文章