iOS Development iOS Data Persistence 2

Question 1

What does `NSFetchRequest` do in Core Data?

Accepted Answer

Defines a query to retrieve managed objects from the persistent store

Answer

`NSFetchRequest` specifies the entity, predicates, sort descriptors, and result type used to query the persistent store.

Question 2

What is a Core Data migration used for?

Accepted Answer

Updating the persistent store schema when the data model changes

Answer

Core Data migration updates the persistent store so it matches a new version of the managed object model without losing existing data.

Question 3

Which format is commonly used to encode Swift objects for local file storage?

Accepted Answer

Both JSON and Plist are common

Answer

Both JSON (via Codable/JSONEncoder) and Property Lists (via PropertyListEncoder) are commonly used to encode Swift objects for local storage.

Question 4

What is CloudKit used for in iOS development?

Accepted Answer

Syncing data across a user's devices and sharing it with other users via iCloud

Answer

CloudKit provides a framework for storing structured data in iCloud and syncing it across a user's devices or sharing with others.

Question 5

Which iOS storage option is best for caching non-critical data that can be recreated?

Accepted Answer

NSCache or the Caches directory

Answer

NSCache and the Caches directory are designed for temporary data that can be regenerated, and the OS may purge them under memory or disk pressure.

iOS Development Practice Test