Core Data overview in iOS Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the primary purpose of Core Data in iOS apps?

Core Data is a framework used in iOS development. What is its main role?

A To manage app navigation and screen transitions

B To handle network requests and API communication

C To create user interface elements and layouts

D To manage the app's data model and persist data locally on the device

💡 Hint

Think about where your app stores data that should stay after closing the app.

Core Data helps apps save, retrieve, and manage data on the device efficiently. It is not for UI or networking.

❓ ui_behavior

intermediate

What happens when you save a managed object context in Core Data?

In Core Data, when you call save() on a managed object context, what is the expected behavior?

A Changes in the context are written to the persistent store on disk

B The app's UI automatically refreshes without any additional code

C The app deletes all stored data from the device

D The app crashes if there are unsaved changes

💡 Hint

Saving means making changes permanent, not deleting or crashing.

Calling save() commits changes in memory to the device's storage so data is not lost.

❓ lifecycle

advanced

Which Core Data component manages the lifecycle of your data objects?

In Core Data, which component is responsible for managing the lifecycle (creation, deletion, and tracking) of your data objects?

A NSFetchRequest

B NSManagedObjectContext

C NSManagedObjectModel

D NSPersistentStoreCoordinator

💡 Hint

This component acts like a workspace where you create and edit data objects.

NSManagedObjectContext tracks changes to data objects and manages their lifecycle before saving.

❓ navigation

advanced

How do you fetch data from Core Data to display in a list?

You want to show saved data in a list on your app screen. Which Core Data class helps you fetch this data?

A NSPersistentContainer

B NSManagedObjectContext

C NSFetchRequest

D NSPredicate

💡 Hint

This class defines what data to get and how to filter it.

NSFetchRequest specifies which data to retrieve from Core Data for display or processing.

🔧 Debug

expert

What error occurs if you try to save a managed object context without setting required attributes?

You created a new Core Data object but forgot to set a required attribute. What error will you get when calling save() on the context?

A NSValidationError

B NSFetchRequestError

C NSPersistentStoreSaveError

D NSManagedObjectContextConcurrencyError

💡 Hint

The error relates to missing or invalid data before saving.

NSValidationError occurs when required attributes are missing or invalid during save.