Load Html Text In Wkwebview

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 {

Solution 1:

Here is a modified version of your ViewController class:

import UIKit
import WebKit

classViewController: UIViewController, UIScrollViewDelegate, WKNavigationDelegate {
    
    @IBOutletweakvar webView: WKWebView!
    @IBOutletweakvar pagesLabel: UILabel!
    
    var readBookNumber =0let headerString ="<meta name=\"viewport\" content=\"initial-scale=1.0\" />"var textSize =3var contentSize: CGSize= .zero

    overridefuncviewDidLoad() {
        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 =falseself.webView.isOpaque =false;
        self.webView.backgroundColor = .clear
        
        // Load Filedo {
            guardlet filePath =Bundle.main.path(forResource: "0", ofType: "html")
                else {
                    print ("File reading error")
                    return
                }
            var content =tryString(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")
        }
    }
    
    overridefuncobserveValue(forKeyPathkeyPath: String?, ofobject: 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 ViewfuncscrollViewDidEndDecelerating(_scrollView: UIScrollView) {
        self.stoppedScrolling()
    }

    funcscrollViewDidEndDragging(_scrollView: UIScrollView, willDeceleratedecelerate: Bool) {
        if!decelerate {
            self.stoppedScrolling()
        }
    }
    
    funcscrollViewDidScroll(_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 =""
        }
    }
    
    funcscrollViewWillBeginZooming(_scrollView: UIScrollView, withview: UIView?) {
        webView.scrollView.pinchGestureRecognizer?.isEnabled =false
    }

    funcstoppedScrolling() {
        let pageToLoad =Int((webView.scrollView.contentOffset.x))
        UserDefaults.standard.set(pageToLoad, forKey: "pageToLoad")
    }
    
    // MARK: - loading webViewfuncwebView(_webView: WKWebView, didStartProvisionalNavigationnavigation: WKNavigation!) {
    }
    
    funcwebView(_webView: WKWebView, didFinishnavigation: 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"))//}
    }

    funcwebView(_webView: WKWebView, didFailnavigation: WKNavigation!, withErrorerror: Error)  {
    }


}

extensionString {
  mutatingfuncchangeHtmlStyle(font: String, fontSize: Int, fontColor: String) {
    let style ="<font face='\(font)' size='\(fontSize)' color= '\(fontColor)'>%@"self=String(format: style, self)
  }
}

It uses an Observer to watch the contentSize change in the web view's scroll view.

Note that it is called multiple times - with different values - during the load and layout process, but it may do the job for you.

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.

Solution 2:

You can add a property observer and watch the estimated progress of the page load:

overridefuncviewDidLoad() {
    super.viewDidLoad()
    webView.addObserver(self, forKeyPath: #keyPath(WKWebView.estimatedProgress), options: .new, context: nil)

....
}

and observe when the page is being loaded:

overridefuncobserveValue(forKeyPathkeyPath: String?, ofobject: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if (keyPath =="estimatedProgress") {
        if webView.estimatedProgress ==1.0 {
            print ("page loaded")
        }
    }
}

You may be able to predict based on the page number how far into the loading process you need to be before you set your offset.

Solution 3:

Instead of observing WKWebView.estimatedProgress you should observe UIScrollView.contentSize because you need to scroll to an available position e.g.:

var positionY: CGFloat=1000var contentSize =CGSize(width: 0, height: 0)

overridefuncviewDidLoad() {
    super.viewDidLoad()
    ...
    webView?.scrollView.addObserver(self, forKeyPath: #keyPath(UIScrollView.contentSize), options: .new, context: nil)
}

overridefuncobserveValue(forKeyPathkeyPath: String?, ofobject: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if (keyPath ==#keyPath(UIScrollView.contentSize)) {
        iflet contentSize = webView?.scrollView.contentSize, contentSize !=self.contentSize {
            self.contentSize = contentSize
            if contentSize.height > positionY {
                webView?.scrollView.setContentOffset(CGPoint(x: 0, y: positionY), animated: true)
            }
        }
    }
}