swift version webview loading page progress bar effect

The example of this article is to share the swift version of webview load page display of the specific code, for your reference, the specific content is as follows

Relatively simple, directly on the code

import UIKit
import WebKit
import SnapKit

class CMWebVC:
UIViewController
, WKNavigationDelegate {
 
 var webUrl: String?
 var webView: WKWebView =WKWebView()
 var progressView:UIProgressView = UIProgressView()
 var closeBtn: UIButton!
 
 override func initVC() {
  webView.addObserver(self, forKeyPath:"estimatedProgress", options: NSKeyValueObservingOptions.new, context:nil)
  webView.navigationDelegate =self
 }
 
 deinit {
  webView.removeObserver(self, forKeyPath:"estimatedProgress")
  webView.navigationDelegate =nil
 }
 
 override func viewDidLoad() {
  super.viewDidLoad()
  
  // webview
  view.addSubview(webView)
  webView.snp.makeConstraints { (make)in
   make.width.height.equalToSuperview()
  }
  
  // progressview
  view.addSubview(progressView)
  progressView.snp.makeConstraints { (make)in
   make.width.equalToSuperview()
   make.height.equalTo(3)
   make.top.equalToSuperview()
  }
  progressView.tintColor =UIColor.ColorBgTheme()
  progressView.isHidden =true
  
  // load url
  if webUrl !=nil {
   webView.load(URLRequest(url:URL(string: webUrl!)!))
  }
  
  // shear
  self.showRightItem(image:"nav_share") {
   
  }
 }
 
 override func viewWillAppear(_ animated:Bool) {
  super.viewWillAppear(animated)
  self.closeButton()
 }
 
 override func viewWillDisappear(_ animated:Bool) {
  self.closeBtn.removeFromSuperview()
 }
 
 func closeButton() {
  if self.closeBtn ==nil {
   self.closeBtn =UIButton(frame: CGRect(x:44, y: 0, width:44, height: 44))
   self.closeBtn.setTitle(" Shut down ", for: .normal)
   self.closeBtn.setTitleColor(UIColor.black, for: .normal)
   self.closeBtn.addAction({ (button)in
    self.navigationController!.popViewController(animated:true)
   })
   self.navigationController?.navigationBar.addSubview(self.closeBtn)
  }
 }
 
 override func observeValue(forKeyPath keyPath:String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
  //  Loading schedule 
  if keyPath == "estimatedProgress" {
   let newprogress = change?[.newKey]!as! Float
   let oldprogress = change?[.oldKey]as? Float ??0.0
   
   // Don't let the progress bar go backwards ... sometimes goback That's what happens 
   if newprogress < oldprogress {
    return
   }
   
   if newprogress == 1 {
    progressView.isHidden =true
    progressView.setProgress(0, animated:false)
   }
   else {
    progressView.isHidden =false
    progressView.setProgress(newprogress, animated:true)
   }
  }
 }
 
 func webView(_ webView:WKWebView, didFinish navigation: WKNavigation!) {
  progressView.isHidden =true
  progressView.setProgress(0, animated:false)
 }
 
 func webView(_ webView:WKWebView, didFail navigation: WKNavigation!, withError error: Error) {
  progressView.isHidden =true
  progressView.setProgress(0, animated:false)
 }
 
 override func navigateBack() {
  if webView.canGoBack {
   webView.goBack()
  }
  else {
   super.navigateBack()
  }
 }
}