get the URL for NSData saved in CoreData

Question

I'm saving a UIImage to Core Data. So first, I convert it to NSData, then save it.

I need to get the URL for the image after it's saved. I'm doing this because I want to schedule a local notification with an attachment, and the only way to do it, AFAIK, is to with a URL.

Here is my code:

//my image:  
var myImage: UIImage?
var imageData: NSData?
    if let image = myImage {
    imageData = UIImageJPEGRepresentation(image, 0.5)! as NSData
}
myEntity.setValue(imageData, forKey: "image")

And that's how I should add an attachment to the notification:
UNNotificationAttachment.init(identifier: String, url: URL>, options: [AnyHashable : Any]?)

I'm saving the image and scheduling the notification manually when the user taps on a button to save the image.

Please let me know if you need extra info.

UIMagagedDocument seems to be a subclass of UIDocument that uses core data, and it initiates with an url to get a context. I’m not very familiar with it, but you may want to look into it. — Antonia Zhang, Dec 29 '18 at 09:54

score 5 · Accepted Answer · answered May 07 '17 at 22:44

5

You can't get the URL. If you configured this property to use external storage then yes, technically there could be a file URL. Maybe. But there's no documented way to get it, and anyway it might not exist after all-- because the external storage setting doesn't require Core Data to use external storage, it just allows it to do so.

If you didn't use that setting then there's never any URL since the image is saved as part of the SQLIte file.

If you need a file URL for the image, save the image to a file separately from Core Data and save the file name as an entity property. Then the file URL is wherever you saved the file.

answered May 07 '17 at 22:44

Tom Harrington

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Thanks, Tom, I got it. – Ennabah May 09 '17 at 00:47
I'm pushing the data saved in Core Data to CloudKit, do you think it's a proper way to use the URL of the CKAsset in the notification? I'm sorry if this is away from the main question. – Ennabah May 09 '17 at 01:06
I've hardly used CloudKit at all, so I can't say for sure. – Tom Harrington May 09 '17 at 02:54

score -1 · Answer 2 · answered Feb 19 '20 at 22:52

And an implementation of how I saved it and then got the URL in practice when I had the same challenge:

Swift 5:

 func getImageURL(for image: UIImage?) -> URL {
            let documentsDirectoryPath:NSString = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as NSString
            let tempImageName = "tempImage.jpg"
            var imageURL: URL?

            if let image = image {

                let imageData:Data = image.jpegData(compressionQuality: 1.0)!
                let path:String = documentsDirectoryPath.appendingPathComponent(tempImageName)
                try? image.jpegData(compressionQuality: 1.0)!.write(to: URL(fileURLWithPath: path), options: [.atomic])
                imageURL = URL(fileURLWithPath: path)
                try? imageData.write(to: imageURL!, options: [.atomic])
            }
            return imageURL!
        }

get the URL for NSData saved in CoreData

2 Answers2