swift -> WKWebView 进度条 加载

参考： http://www.jianshu.com/p/367952852c6d

webView.addObserver(self, forKeyPath: "estimatedProgress", options: .new, context: nil)
//

 override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        
        if ((object as AnyObject).isEqual(webView) && (keyPath == "estimatedProgress")) {
            
        
            progeress!.setProgress(Float(webView.estimatedProgress), animated: true)
            if(webView.estimatedProgress>=1){
                progeress.isHidden = true;
                progeress!.setProgress(0, animated: false);
            }else{
                
                progeress.isHidden = false;
                progeress!.setProgress(Float(webView.estimatedProgress), animated: true);
            }
            print(webView.estimatedProgress);
            
        }
    }