How to Fetch NSManagedObject from Core data given its type and property - core-data

Question

I need to get a NSManagedObject from Core data so I can share it with cloud Kit. I fetch the result based on the entity property and type. Then I try to convert the result into NSManagedObject.
// Fetch NSManagedObject so it can be shared
if let estProfile: NSManagedObject = fetchEntity(uniqueId: self.energyProfileId!, entityType: EstEnergyProfile.self) {
print("fetched NSManagedObject for sharing with cloud kit")
}
//Fetch NSManagedObject given specific property and its type
func fetchEntity (uniqueId: String, entityType: NSManagedObject.Type) -> NSManagedObject?{
var obj: NSManagedObject? = nil
let context = appDelegate.persistentContainer.viewContext
do {
let fetchRequest: NSFetchRequest<NSFetchRequestResult> = entityType.fetchRequest()
fetchRequest.predicate = NSPredicate(format: "uniqueId == %#", uniqueId)
let fetchedResults = try context.fetch(fetchRequest)
obj = fetchedResults.first as NSManagedObject
}
catch {
print("Error fetching entity: ", entityType)
}
return obj
}
In the above code at the line
obj = fetchedResults.first as NSManagedObject
I get the error : 'NSFetchRequestResult?' is not convertible to 'NSManagedObject
I don't think I am doing this right. Can someone help fix this code?

Answer 1

I would make the fetch function generic
func fetchEntity<EntityType: NSManagedObject>(_: EntityType.Type, uniqueId: String) -> EntityType? {
let context = appDelegate.persistentContainer.viewContext
do {
let fetchRequest = EntityType.fetchRequest()
fetchRequest.predicate = NSPredicate(format: "uniqueId == %#", uniqueId)
let fetchedResults = try context.fetch(fetchRequest)
return fetchedResults.first as? EntityType
}
catch {
print("Error fetching entity: ", error)
return nil
}
}
Example
let estProfile: NSManagedObject = fetchEntity(EstEnergyProfile.self, uniqueId: self.energyProfileId!)