上傳圖片和評論到coredata

重點是     let imageData = UIImagePNGRepresentation(imageView.image!)

先把  image 轉換成   imageData,  才能存進去  core data..   coredata的這個欄位的type要選  binary data

 @IBAction func postImageAction(_ sender: UIButton) {

        

        let appDelegate = UIApplication.shared.delegate as! AppDelegate

        let context     = appDelegate.persistentContainer.viewContext

        

        let newPost     = NSEntityDescription.insertNewObject(forEntityName: "Posts", into: context)

        

        newPost.setValue(currentUser, forKey: "username")

        newPost.setValue(messageTextField.text, forKey: "message")

        let imageData = UIImagePNGRepresentation(imageView.image!)

        

        newPost.setValue(imageData, forKey: "image")

        

        

        do{

            try context.save()

            self.imageView.image = UIImage(named: "Placeholder-image.png")

            self.messageTextField.text = ""

            

            createAlert(title: "已上傳", message: "你的評論已經成功上傳")

            

        }catch{

            print("Could not save data.")

            createAlert(title: "上傳失敗", message: "請用戶稍後再試")

        }