Swift4.0版-H5页面实现长按保存图片

• 刚开始拿到需求还是比较尴尬的,不会啊,没做过啊,是不是就尴尬了
• 随即想了一下,好像微信里好多H5页面都有这样的功能
• 然后查阅了一下相关资料,发现两行核心代码

//获取长按所在点
let urlString = "document.elementFromPoint(\(touchPoint.x), \(touchPoint.y)).src"

//根据该点的参数获取对应图片的链接
let saveUrl = webView.stringByEvaluatingJavaScript(from: urlString)

下面来一起啊看一下完整的代码步骤

首先给UiWebView加一个长按手势

//添加长按手势
let longPressGes = UILongPressGestureRecognizer(target: self, action: #selector(longPressedGesture(_:)))
//一定要遵循代理
longPressGes.delegate = self
webView.addGestureRecognizer(longPressGes)

实现代理方法

//不实现该代理方法,长按无效
//MARK: 手势代理方法
extension SIWebViewController : UIGestureRecognizerDelegate{
    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return true
    }
}

接着在手势响应方法里面实现相应的功能

注意:

• 一定要判断手势的state属性
• 判断saveUrl是否是一个nil值

@objc func longPressedGesture(recognizer: UILongPressGestureRecognizer){
    if recognizer.state != .began { return }
        
   let touchPoint = recognizer.location(in: webView)
    
    //核心代码
    let urlString = "document.elementFromPoint(\(touchPoint.x), \(touchPoint.y)).src"
   if let saveUrl = webView.stringByEvaluatingJavaScript(from: urlString) {
        //判断图片的链接是否为空,长度是否为o
        if saveUrl.characters.count == 0 { return }
        addAlertAction(saveUrl)
    }
}

调用保存图片功能按钮

fileprivate func addAlertAction(imageStr: String){
        let alertV = UIAlertController()
        let saveAction = UIAlertAction(title: "保存图片", style: .default) { (alertV) in
            self.saveImageToDisk(imageStr)
        }
        //取消保存不作处理
        let cancelAction = UIAlertAction(title: "取消", style: .cancel, handler: nil)
        
        alertV.addAction(saveAction)
        alertV.addAction(cancelAction)
        controller.present(alertV, animated: true, completion: nil)
}

使用SDWebImage保存图片

• 注意使用SDWebImage的缓存机制

    //保存图片
    fileprivate func saveImageToDisk(_ imageStr: String){
        guard let imageUrl = URL(string: imageStr) else { return }
        let sdManager = SDWebImageManager.shared()
        
        var image : UIImage!
        if (sdManager?.diskImageExists(for: imageUrl))! {
           //先从缓存中查找图片
            image = sdManager?.imageCache.imageFromDiskCache(forKey: imageUrl.absoluteString)
        }else{
           //缓存中没有图片在进行网络下载
            let data = try! Data(contentsOf: imageUrl)
            image = UIImage(data: data)
        }
        
        //保存图片到相册中
        UIImageWriteToSavedPhotosAlbum(image, self, #selector(self.image(_:didFinishSavingWithError:contextInfo:)), nil)
    }

最后是一个保存成功与否的回调方法

@objc func image(_ image: UIImage, didFinishSavingWithError: NSError?, contextInfo: AnyObject){
    if didFinishSavingWithError != nil {
        MBProgressHUD.show(string: "请开启访问相册权限后使用此功能", inView: self.view)
    } else {
        MBProgressHUD.show(string: "图片保存成功", inView: self.view)
    }
}

以上如有不妥之处还望多多指正