在 Realm 中保存图像

Question

我正在尝试从设备的照片库中选择图片的方法：

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any])
{

    userPhoto.image = info[UIImagePickerControllerOriginalImage] as! UIImage?
    userPhoto.contentMode = .scaleAspectFill
    userPhoto.clipsToBounds = true

    dismiss(animated: true, completion: nil)
}

并将这张图片保存在 Realm 中（作为 NSData）：

asset.assetImage = UIImagePNGRepresentation(userPhoto.image!)! as NSData?

...

   try! myRealm.write
        {
            user.assetsList.append(asset)
            myRealm.add(user)
        }

构建成功并尝试选择并保存图像（在应用程序中）后，我遇到应用程序错误： '二进制太大'

我做错了什么？

附：对不起我的英语:)

---

经过一些操作后，我得到了这段代码。但它会覆盖我的图像。

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any])
{
    let imageUrl = info[UIImagePickerControllerReferenceURL] as! NSURL
    let imageName = imageUrl.lastPathComponent
    let documentDirectory = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first!
    let photoURL = NSURL(fileURLWithPath: documentDirectory)
    let localPath = photoURL.appendingPathComponent(imageName!)
    let image = info[UIImagePickerControllerOriginalImage]as! UIImage
    let data = UIImagePNGRepresentation(image)

    do
    {
        try data?.write(to: localPath!, options: Data.WritingOptions.atomic)
    }
    catch
    {
        // Catch exception here and act accordingly
    }

    userPhoto.image = image
    userPhoto.contentMode = .scaleAspectFill
    userPhoto.clipsToBounds = true

    urlCatch = (localPath?.path)!
    self.dismiss(animated: true, completion: nil);
}

Answer 1

不要将图像本身保存到领域，只需将图像的位置作为字符串或 NSString 保存到领域，然后从该保存的路径加载图像。性能方面，从该物理位置加载图像总是更好，并且您的数据库不会变得太大

  func loadImageFromPath(_ path: NSString) -> UIImage? {

        let image = UIImage(contentsOfFile: path as String)

        if image == nil {
            return UIImage()
        } else{
            return image
        }
    }

或者你只是保存图像名称，如果它在你的文档目录中的话

func loadImageFromName(_ imgName: String) -> UIImage? {

        guard  imgName.characters.count > 0 else {
            print("ERROR: No image name")
            return UIImage()
        }

        let imgPath = Utils.getDocumentsDirectory().appendingPathComponent(imgName)
        let image = ImageUtils.loadImageFromPath(imgPath as NSString)           
        return image    
    }

这里是一个粗略的示例，如何使用唯一名称将捕获的图像保存到您的目录：

    @IBAction func capture(_ sender: AnyObject) {

        let videoConnection = stillImageOutput?.connection(withMediaType: AVMediaTypeVideo)
            stillImageOutput?.captureStillImageAsynchronously(from: videoConnection, completionHandler: { (imageDataSampleBuffer, error) -> Void in

                let imageData = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(imageDataSampleBuffer)
                //self.stillImage = UIImage(data: imageData!)
                //self.savedImage.image = self.stillImage

                let timestampFilename = String(Int(Date().timeIntervalSince1970)) + "someName.png"

                let filenamePath =  URL(fileReferenceLiteralResourceName: getDocumentsDirectory().appendingPathComponent(timestampFilename))
                let imgData = try! imageData?.write(to: filenamePath, options: [])

            })



    /* helper get Document Directory */
    class func getDocumentsDirectory() -> NSString {
        let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
        let documentsDirectory = paths[0]
        //print("Path: \(documentsDirectory)")
        return documentsDirectory as NSString
    }

Answer 2

https://realm.io/docs/objc/latest/#current-limitations 最大数据大小为 16 MB。这是领域的限制

Answer 3

根据您序列化图像数据的方式（例如，如果它是无损位图），该数据很可能超过 16MB，正如您所说，这是 Realm 支持的二进制属性的最大大小。

当你调用 NSData.length 时，它说你的数据有多大？