给WKWebView添加进度条（swift）

在WKWebView上添加进度条比在UIWebView上简单了许多，并且是真的进度了，不用再自己去算比例或者造假的进度条了，

废话少说，进入正题吧：

首先WKWebView有个属性 UIProgressView

    /** 进度条 */
    var progressView : UIProgressView? = nil
    let keyPathForProgress : String = "estimatedProgress"

override func viewDidLoad() {
        super.viewDidLoad()

        initWebView()
        initProgressView()
    }

override func viewWillLayoutSubviews() {
        let width = self.view.bounds.size.width;
        let height = self.view.bounds.size.height;
        let statusBarBounds = UIApplication.sharedApplication().statusBarFrame
        
        let webViewHeight = height - 64 - 49
        webView.frame = CGRectMake(0, 64, width, webViewHeight)
        
    }

WKWebView代理

private func initWebView() {
        webView.navigationDelegate = self
        webView.UIDelegate = self
    }

WKWebView有一个属性estimatedProgress，就是当前网页加载的进度，所以首先监听这个属性。

private func initProgressView() {

        progressView = UIProgressView.init(frame: CGRectMake(0, 0, UILayoutDefine.KScreenWidth, 4))
　　　　　　// 这里可以改进度条颜色
        progressView!.tintColor = UIColor.greenColor()
        webView.addSubview(progressView!)
　　　　　　// 监听
　　　　　　webView.addObserver(self, forKeyPath: keyPathForProgress, options: [NSKeyValueObservingOptions.New, NSKeyValueObservingOptions.Old], context: nil) 7 8 }

实现代理方法

/** 计算进度条 */
    override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
        if ((object?.isEqual(webView) != nil) && (keyPath! == keyPathForProgress) != nil) {
            let newProgress = change![NSKeyValueChangeNewKey]?.floatValue
            let oldProgress = change![NSKeyValueChangeOldKey]?.floatValue
            
            if newProgress < oldProgress {
                return
            }
            
            if newProgress >= 1 {
                progressView!.hidden = true
                progressView!.setProgress(0, animated: false)
            } else {
                progressView!.hidden = false
                progressView!.setProgress(newProgress!, animated: true)
            }
        } else {
            super.observeValueForKeyPath(keyPath, ofObject: object, change: change, context: context)
        }
    }

/**
     移除消息通知
     */
    deinit {
        webView .removeObserver(self, forKeyPath: keyPathForProgress)
        webView.navigationDelegate = nil
        webView.UIDelegate = nil
    }

OK 完成

参考：http://nshipster.cn/wkwebkit/