Store image in Core Data in swift - swift

Question

i'm trying to save a local image in my app to the core data model. I have created the entity and created an attribute for the image. But when i run the app it crashes with this error, Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unacceptable type of value for attribute: property = "image"; desired type = NSData; given type = UIImage; value = <UIImage: My code to save image is,
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let context = appDelegate.persistentContainer.viewContext
let entity = NSEntityDescription.entity(forEntityName: "Saloon", in: context)
let newUser = NSManagedObject(entity: entity!, insertInto: context)
newUser.setValue(nameLbl.text, forKey: "name")
newUser.setValue(addressLbl.text, forKey: "address")
newUser.setValue(distanceLbl.text, forKey: "distance")
newUser.setValue(rating.text, forKey: "rating")
newUser.setValue(imageView.image, forKey: "image") as? UIImage
do {
try context.save()
print("saved")
} catch {
print("Failed saving")
}
This is how i'm fetching the image,
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let context = appDelegate.persistentContainer.viewContext
let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Saloon")
//request.predicate = NSPredicate(format: "age = %#", "12")
request.returnsObjectsAsFaults = false
do {
let result = try context.fetch(request)
for data in result as! [NSManagedObject] {
print(data.value(forKey: "name") as! String)
let image: Data = data.value(forKey: "image")! as! Data
let decodedimage = UIImage(data: image)
imageView2.image = decodedimage
name2Lbl.text = data.value(forKey: "name") as? String
address2Lbl.text = data.value(forKey: "address") as? String
distance2Lbl.text = data.value(forKey: "distance") as? String
rating2Lbl.text = data.value(forKey: "rating") as? String
}
} catch {
print("Failed")
}

Answer 1

You cannot save a UIImage directly in Core Data. Instead, you’ll have to convert the image to NSData (as in “desired type = NSData” in your error message). Here’s a UIImage extension for that:
extension UIImage {
func jpegData(withCompressionQuality quality: CGFloat) -> Data? {
return autoreleasepool(invoking: {() -> Data? in
return UIImageJPEGRepresentation(self, quality)
})
}
}
The quality is a value from 0.0 through 1.0 with the latter representing the maximum quality of the JPEG compressed image. The use of autoreleasepool helps avoid occasional memory leakage problems observed when using UIImageJPEGRepresentation.
You can then save the image using this code:
if let imageData = imageView.image .jpegData(withCompressionQuality: 1.0) {
newUser.setValue(imageData, forKey: "image")
}
BTW, you can also convert to PNG instead of JPEG which is lossless if this is what you need. Use UIImagePNGRepresentation instead of UIImageJPEGRepresentation.

Answer 2

Deferring from the previous answer, it is possible to store images in Core Data as UIImage. Although this is not considered to be good practice as Databases are not meant for storing files. We don't use core data to store the images directly instead we use the file path to where the image data is stored on your phone.
Anyways, the best method I found out while developing a side-project is demonstrated below
Set the entity codeGen to Manual/None
Select the attribute you want to be of Image type and choose transformable as it's type
Enter Custom class identifier as UIImage
Go to editor and select Create NSManagedObject Subclass
The Process will create 2 swift files depending on the number of your entities(I only had 1 entity). Now, select the <EntityName> + CoreDataProperties.swift file and import UIKit
If, on clicking Jump to Definition for the #NSManaged public var <attributeName: UIImage? you are able to land on the UIImage definition your work is done.
Perform actions on the entities just like you would and you will be able to fetch, save, edit the image attribute by down-casting <EntityName>?.value(forKey: "<attributeName>") as? UIImage.
I had to use the entity as NSManagedObject type and was for some reason not able to access the image directly from the created subclass.