在WKWebView中加载html文本 [英] Load html text in WKWebView
问题描述
我使用此代码以 WKWebView 中的文本加载 html 文件:
I use this code to load my html file with text in WKWebView:
do {
guard let filePath = Bundle.main.path(forResource: "\(readBookNumber)", ofType: "html")
else {
print ("File reading error")
return
}
var content = try String(contentsOfFile: filePath, encoding: .utf8)
let baseUrl = URL(fileURLWithPath: filePath)
content.changeHtmlStyle(font: "Iowan-Old-Style", fontSize: UserDefaults.standard.integer(forKey: "textSize"), fontColor: textColor)
webView.loadHTMLString(headerString+content, baseURL: baseUrl)
}
catch {
print ("File HTML error")
}
和此代码可加载用户上次停止阅读的页面:
and this code to load the page where the user stopped reading last time:
self.webView.scrollView.contentOffset.x = CGFloat(UserDefaults.standard.integer(forKey: "pageToLoad"))
我使用此方法使用代码加载最后一页:
I use code for loading last page in this method:
func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
self.webView.scrollView.contentOffset.x = CGFloat(UserDefaults.standard.integer(forKey: "pageToLoad"))
}
}
起初，我使用了 deadline:.now()+ 0.1 ，但这没有用.因为最后读取的页面是最初加载的，所以几秒钟后，我在第一页上看到了我的文本.我将其更改为 deadline:.now()+ 0.5 ，并且从读取的最后一页开始加载文本.是700页.但是现在我想加载1700页的其他文本.我也有像第一次一样的问题.我可以更改截止日期:.now()+ 1.0 ，我的文本会很好地加载.但是我认为这不是最好的解决方案.我在iPhone X上运行它.但是，如果在iPad mini 2上运行它，则应该更改 deadline:.now()+ 10.0 ，因为iPad mini 2的功能不是很强大.如何解决问题?
At first I used deadline: .now() + 0.1, but that didn't work. Because the last read page was loaded initially, and after a few seconds I see my text on the first page. I change it to deadline: .now() + 0.5 and the text loads fine from the last page read. Its was 700 pages. But now I want to load another text with 1700 pages. And I have same problem like first time. I can change deadline: .now() + 1.0 and my text will load fine. But I think this is not the best solution. I run it on my iPhone X. But maybe if I run it on iPad mini 2 I should change deadline: .now() + 10.0 because iPad mini 2 not very powerful. How to solve the problem?
根据@DPrice代码进行更新:
如果我使用此代码:
override func viewDidLoad() {
super.viewDidLoad()
webView.addObserver(self, forKeyPath: #keyPath(WKWebView.estimatedProgress), options: .new, context: nil)
....
}
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
if (keyPath == "estimatedProgress") {
if webView.estimatedProgress == 1.0 {
self.webView.scrollView.contentOffset.x = CGFloat(UserDefaults.standard.integer(forKey: "pageToLoad\(self.readBookNumber)"))
}
}
}
我的代码中有同样糟糕的结果.
I have same bad result like in my code.
但是，如果我使用以下代码:
But if I use this code:
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
if (keyPath == "estimatedProgress") {
if webView.estimatedProgress == 1.0 {
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
self.webView.scrollView.contentOffset.x = CGFloat(UserDefaults.standard.integer(forKey: "pageToLoad\(self.readBookNumber)"))
}
}
}
}
一切正常.我的最后一页加载正常.但这并不能解决我的问题.
Everything works fine. And my last page loading fine. But it does not solve the problem in my question.
推荐答案
这是 ViewController 类的修改版本:
import UIKit
import WebKit
class ViewController: UIViewController, UIScrollViewDelegate, WKNavigationDelegate {
@IBOutlet weak var webView: WKWebView!
@IBOutlet weak var pagesLabel: UILabel!
var readBookNumber = 0
let headerString = "<meta name=\"viewport\" content=\"initial-scale=1.0\" />"
var textSize = 3
var contentSize: CGSize = .zero
override func viewDidLoad() {
super.viewDidLoad()
// Web View Delegate
webView.scrollView.delegate = self
webView.navigationDelegate = self
webView.scrollView.isPagingEnabled = true
webView.scrollView.alwaysBounceVertical = false
webView.scrollView.showsHorizontalScrollIndicator = true
webView.scrollView.showsVerticalScrollIndicator = false
webView.scrollView.panGestureRecognizer.isEnabled = false
webView.scrollView.pinchGestureRecognizer?.isEnabled = false
webView.scrollView.bouncesZoom = false
self.webView.isOpaque = false;
self.webView.backgroundColor = .clear
// Load File
do {
guard let filePath = Bundle.main.path(forResource: "0", ofType: "html")
else {
print ("File reading error")
return
}
var content = try String(contentsOfFile: filePath, encoding: .utf8)
let baseUrl = URL(fileURLWithPath: filePath)
content.changeHtmlStyle(font: "Iowan-Old-Style", fontSize: 4, fontColor: "black")
webView.loadHTMLString(headerString+content, baseURL: baseUrl)
// add content size Observer
webView.scrollView.addObserver(self, forKeyPath: #keyPath(UIScrollView.contentSize), options: .new, context: nil)
}
catch {
print ("File HTML error")
}
}
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
if (keyPath == #keyPath(UIScrollView.contentSize)) {
let contentSize = webView.scrollView.contentSize
if contentSize != self.contentSize {
self.contentSize = contentSize
DispatchQueue.main.async {
self.webView.scrollView.contentOffset.x = CGFloat(UserDefaults.standard.integer(forKey: "pageToLoad"))
}
}
}
}
// MARK: - webView Scroll View
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
self.stoppedScrolling()
}
func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
if !decelerate {
self.stoppedScrolling()
}
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
var currentPage = Int((webView.scrollView.contentOffset.x / webView.scrollView.frame.size.width) + 1)
let pageCount = Int(webView.scrollView.contentSize.width / webView.scrollView.frame.size.width)
if currentPage == 0 {
currentPage = 1
} else {
}
if !webView.isHidden {
pagesLabel.text = "\( currentPage ) из \( pageCount )"
} else {
pagesLabel.text = ""
}
}
func scrollViewWillBeginZooming(_ scrollView: UIScrollView, with view: UIView?) {
webView.scrollView.pinchGestureRecognizer?.isEnabled = false
}
func stoppedScrolling() {
let pageToLoad = Int((webView.scrollView.contentOffset.x))
UserDefaults.standard.set(pageToLoad, forKey: "pageToLoad")
}
// MARK: - loading webView
func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {
}
func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
// Маленькая задержка, которую мне хотелось бы использовать
/*DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
self.webView.scrollView.contentOffset.x = CGFloat(UserDefaults.standard.integer(forKey: "pageToLoad"))
}*/
// Большая задержка, которую мне приходится использовать
// don't do this here... we'll do the "auto-scroll" inside the change contentSize Observer
//DispatchQueue.main.asyncAfter(deadline: .now() + 2.0) {
// self.webView.scrollView.contentOffset.x = CGFloat(UserDefaults.standard.integer(forKey: "pageToLoad"))
//}
}
func webView(_ webView: WKWebView, didFail navigation: WKNavigation!, withError error: Error) {
}
}
extension String {
mutating func changeHtmlStyle(font: String, fontSize: Int, fontColor: String) {
let style = "<font face='\(font)' size='\(fontSize)' color= '\(fontColor)'>%@"
self = String(format: style, self)
}
}
它使用观察器来观察Web视图的滚动视图中 contentSize 的变化.
It uses an Observer to watch the contentSize change in the web view's scroll view.
请注意，在加载和布局过程中，它被多次调用(具有不同的值)，但它可能为您完成工作.
Note that it is called multiple times - with different values - during the load and layout process, but it may do the job for you.
不过，还请注意，您需要考虑网络视图尺寸的变化-例如，如果用户旋转设备.所以...还有更多事情要做，但这可能会让您前进.
Also note, though, that you'll need to account for changes in the web view size - for example, if the user rotates the device. So... more to do, but this may get you going.
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