how to save uiimage into core data as pngdata - swift

Question

In my swift code below the goal is to save a uiimage using pngdata into core data. The problem is right now it does not appear to be saving because "test numbers" is not being printed into the debug section. I don't know how to make sure its being save. I am looking to save the image and verify its there.
override func viewDidLoad() {
super.viewDidLoad()
let gwen = UIImage(named: "f.jpeg")
if let imageData = gwen.self?.pngData() {
DataBaseHelper.shareInstance.saveImage(data: imageData)
}
let arr = DataBaseHelper.shareInstance.fetchImage()
print("test number : ",arr)
}
Other Class
class DataBaseHelper {
static let shareInstance = DataBaseHelper()
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
func saveImage(data: Data) {
let imageInstance = Info(context: context)
imageInstance.img = data
do {
try context.save()
print("Image is saved")
} catch {
print(error.localizedDescription)
}
}
func fetchImage() -> [Info] {
var fetchingImage = [Info]()
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Info")
do {
fetchingImage = try context.fetch(fetchRequest) as! [Info]
} catch {
print("Error while fetching the image")
}
return fetchingImage
}
}

Answer 1

It is a bad approach to saving image in core data!
For saving heavy documents iOS provides you document directory folder which is fast and efficient to save and retrieve than core data and user defaults.
Core data is an sqlite table which is just light weight properties like strings, numbers and Date etc.
Here is a trick you just save your image in document directory folder of your application which has large space and save the reference/ filename into core data.
Rather than creating data property you should have to create imageName property
import Foundation
import CoreData
extension Info {
#nonobjc public class func fetchRequest() -> NSFetchRequest<Info> {
return NSFetchRequest<Info>(entityName: "Info")
}
#NSManaged public var imageName: String?
}
extension Info : Identifiable {
}
After that add this extension for save and get image from document folder
extension UIImage {
func save(to fileName:String) {
let documentsUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!;
let fileURL = documentsUrl.appendingPathComponent(fileName)
if let imageData = self.jpegData(compressionQuality: 1) {
try? imageData.write(to: fileURL, options: .atomic)
}
}
convenience init(fileName: String) {
var data = Data()
let documentsUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!;
let fileURL = documentsUrl.appendingPathComponent(fileName)
do {
let imageData = try Data(contentsOf: fileURL)
data = imageData
} catch {
print(error.localizedDescription)
}
self.init(data: data)!
}
}
then how you can save and retrieve reference in core data and image document folder.
class ViewVC:UIViewController {
var images:[UIImage] = [] {
didSet {
print(images.count)
// reload tableView or collectionView
}
}
override func viewDidLoad() {
super.viewDidLoad()
}
func saveImage(image:UIImage,fileName:String) {
image.save(to: fileName)
DataBaseHelper.shareInstance.saveImage(fileName: fileName)
}
func getImage() {
let allInfo = DataBaseHelper.shareInstance.fetchInfo()
for info in allInfo {
if let name = info.imageName {
let image = UIImage(fileName: name)
self.images.append(image)
}
}
}
}
you helper class
class DataBaseHelper {
static let shareInstance = DataBaseHelper()
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
func saveImage(fileName: String) {
let imageInstance = Info(context: context)
imageInstance.imageName = fileName
do {
try context.save()
print("Image name is saved")
} catch {
print(error.localizedDescription)
}
}
func fetchInfo() -> [Info] {
var fetchingImage = [Info]()
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Info")
do {
fetchingImage = try context.fetch(fetchRequest) as! [Info]
} catch {
print("Error while fetching the image")
}
return fetchingImage
}
}