iOS 对当前webView进行截屏的方法

func getImage(context: ServiceExecuteContext) -> UIImage { 
    //创建一个基于位图的图形上下文并指定大小 
    UIGraphicsBeginImageContextWithOptions(context.fromViewController.webView.bounds.size, true, 0) 
    //renderInContext呈现接受者及其子范围到指定的上下文 
    context.fromViewController.webView.layer.renderInContext(UIGraphicsGetCurrentContext()!) 
    //返回一个基于当前图形上下文的图片 
    let image = UIGraphicsGetImageFromCurrentImageContext() 
    //移除栈顶的基于当前位图的图形上下文 
    UIGraphicsEndImageContext() 
     
    //let imagRef = CGImageCreateWithImageInRect((image?.CGImage)!, context.fromViewController.webView.bounds) 
    //let newImage = UIImage.init(CGImage: imagRef!) 
    //UIImageWriteToSavedPhotosAlbum(newImage, nil, nil, nil);//保存图片到照片库 
    return image! 
  } 

func getImage(context: ServiceExecuteContext) -> UIImage { 
     
    UIGraphicsBeginImageContextWithOptions(context.fromViewController.webView.bounds.size, true, 0) 
    for subView: UIView in context.fromViewController.webView.subviews { 
      subView.drawViewHierarchyInRect(subView.bounds, afterScreenUpdates: true) 
    } 
    //UIApplication.sharedApplication().keyWindow?.layer.renderInContext(UIGraphicsGetCurrentContext()!) 
    let image = UIGraphicsGetImageFromCurrentImageContext() 
    UIGraphicsEndImageContext() 
     
    //let imagRef = CGImageCreateWithImageInRect((image?.CGImage)!, context.fromViewController.webView.bounds) 
    //let newImage = UIImage.init(CGImage: imagRef!) 
     
    return image! 
  }