[iOS] Core Data CRUD (Create, Read, Update, Delete) 구현

Core Data에서 데이터를 저장(Create), 불러오기(Read), 수정(Update), 삭제(Delete)하는 기본적인 CRUD 기능을 구현하는 방법 정리

1. Core Data 스택 설정

   import CoreData
   
   class CoreDataManager {
       static let shared = CoreDataManager()
       
       let persistentContainer: NSPersistentContainer = {
           let container = NSPersistentContainer(name: "MyAppModel")
           container.loadPersistentStores { _, error in
               if let error = error {
                   fatalError("Core Data error: \(error)")
               }
           }
           return container
       }()
       
       var context: NSManagedObjectContext {
           return persistentContainer.viewContext
       }
   }

2. 데이터 생성(Create)

   func createUser(name: String, email: String) {
       let user = UserEntity(context: CoreDataManager.shared.context)
       user.name = name
       user.email = email
       
       saveContext()
   }

3. 데이터 불러오기(Read)

   func fetchUsers() -> [UserEntity] {
       let request: NSFetchRequest<UserEntity> = UserEntity.fetchRequest()
       do {
           return try CoreDataManager.shared.context.fetch(request)
       } catch {
           print("Fetch error: \(error)")
           return []
       }
   }

4. 데이터 수정(Update)

   func updateUser(user: UserEntity, newName: String) {
       user.name = newName
       saveContext()
   }

5. 데이터 삭제(Delete)

   func deleteUser(user: UserEntity) {
       CoreDataManager.shared.context.delete(user)
       saveContext()
   }

6. 공통 저장 함수(saveContext)

   func saveContext() {
       let context = CoreDataManager.shared.context
       if context.hasChanges {
           do {
               try context.save()
           } catch {
               print("Save error: \(error)")
           }
       }
   }