WKWebview Swift 4 UIProgressBar 不起作用 Xcode 9

Question

我正在尝试添加一个在 WKWebview 加载时填充的进度条。我已经尝试使用下面的代码。

导入 UIKit 导入 WebKit 类 GmailViewController：UIViewController、WKUIDelegate、WKNavigationDelegate{

@IBOutlet weak var progressView: UIProgressView!
@IBOutlet weak var contentView: UIView!
@IBOutlet weak var webView: WKWebView!
@IBAction func homeBtn(_ sender: Any) {
     self.performSegue(withIdentifier: "HomeScreen", sender: self)
}
override func viewDidLoad() {
    super.viewDidLoad()
    let webConfiguration = WKWebViewConfiguration()
    webConfiguration.websiteDataStore = WKWebsiteDataStore.default()
    let webView = WKWebView(frame: .zero, configuration: webConfiguration)
    webView.navigationDelegate = self
    webView.uiDelegate = self
    self.webView = webView
    if let webView = self.webView
    {
        view.addSubview(webView)
        webView.translatesAutoresizingMaskIntoConstraints = false
        let height = NSLayoutConstraint(item: webView, attribute: .height, relatedBy: .equal, toItem: self.contentView, attribute: .height, multiplier: 1, constant: 0)
        let width = NSLayoutConstraint(item: webView, attribute: .width, relatedBy: .equal, toItem: self.contentView, attribute: .width, multiplier: 1, constant: 0)
        let offset = NSLayoutConstraint(item: webView, attribute: .top, relatedBy: .equal, toItem: self.contentView, attribute: .top, multiplier: 1, constant: 0)
        view.addConstraints([height, width, offset])
    }
    let myURL = URL(string: "https://gmail.com/mail")
    let myRequest = URLRequest(url: myURL!)
    webView.load(myRequest)
    progressView = UIProgressView(progressViewStyle: .default)
    progressView.sizeToFit()
    // Set frame to exact below of navigation bar if available
    progressView.frame = CGRect(x: 0, y: 64, width: self.view.bounds.size.width, height: 20)
    self.view.addSubview(progressView)
    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" {
        print("estimatedProgress")
        progressView.progress = Float(webView.estimatedProgress)
    }}
  }

由于某些奇怪的原因，它在运行时返回错误 cannot set event for nil。

Answer 1

这是您问题的完整工作解决方案。

斯威夫特 4

import UIKit
import WebKit
import PlaygroundSupport

class MyViewController : UIViewController,WKNavigationDelegate,WKUIDelegate {
    var webView : WKWebView!
    var progressView : UIProgressView!

    override func viewDidLoad() {
        super.viewDidLoad()

        let site = "http://google.com"
        let url = URL(string: site)
        let request = URLRequest(url: url!)
        webView = WKWebView(frame: self.view.frame)
        webView.navigationDelegate = self
        webView.uiDelegate = self
        webView.load(request)
        self.view.addSubview(webView)

        progressView = UIProgressView(progressViewStyle: .default)
        progressView.sizeToFit()
        // Set frame to exact below of navigation bar if available
        progressView.frame = CGRect(x: 0, y: 64, width: self.view.bounds.size.width, height: 20)
        self.view.addSubview(progressView)

        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" {
            print("estimatedProgress")
            progressView.progress = Float(webView.estimatedProgress)
        }
    }
}