全原生,无添加

extension UIImageView{
    func downloadedFrom(imageurl : String){
        if imageurl.isEmpty {
            return
        }
        let newUrl = imageurl.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed)
        //创建URL对象
        let url = URL(string: newUrl!)!
        //创建请求对象
        let request = URLRequest(url: url)
        
        let session = URLSession.shared
        let dataTask = session.dataTask(with: request, completionHandler: {
            (data, response, error) -> Void in
            if error != nil{
                print(error.debugDescription)
            }else{
                //将图片数据赋予UIImage
                let img = UIImage(data:data!)
                
                // 这里需要改UI，需要回到主线程
                DispatchQueue.main.async {
                    self.image = img
                }
                
            }
        }) as URLSessionTask
        
        //使用resume方法启动任务
        dataTask.resume()
    }
    func dowloadFromServer(url: URL, contentMode mode: UIView.ContentMode = .scaleAspectFit) {
        contentMode = mode
        URLSession.shared.dataTask(with: url) { data, response, error in
            guard
                let httpURLResponse = response as? HTTPURLResponse, httpURLResponse.statusCode == 200,
                let mimeType = response?.mimeType, mimeType.hasPrefix("image"),
                let data = data, error == nil,
                let image = UIImage(data: data)
                else { return }
            DispatchQueue.main.async() {
                self.image = image
            }
            }.resume()
    }
    func dowloadFromServer(link: String, contentMode mode: UIView.ContentMode = .scaleAspectFit) {
        guard let url = URL(string: link) else { return }
        dowloadFromServer(url: url, contentMode: mode)
    }
    
}