Core Data Concurrency - Query

query_concurrently.swift

static func searchUserBy(id: Int, in context: NSManagedObjectContext, completionHandler: @escaping (_ managedObjects: User?) -> Void) {
    context.perform {
        //searching core data 
        let request = NSFetchRequest<NSFetchRequestResult>(entityName: "User")
        request.returnsObjectsAsFaults = false
        request.predicate = NSPredicate(format: "id == %@", "\(id)")
        
        do {
            let results = try context.fetch(request)
            if let managedObjects = results as? [NSManagedObject], let user = managedObjects.first {
                completionHandler(user)
            } else {
                completionHandler(nil)	
            }
        } catch {
            print(error)
            completionHandler(nil)
        }
    }
}