When deciding between Core Data and NSUserDefaults for data persistence in an iOS application, the choice largely depends on the nature and complexity of the data you need to store.
When to Use Core Data
Core Data is a powerful framework designed for managing complex data models and relationships. It is suitable for:
Large Data Sets: Core Data is optimized for handling large amounts of data efficiently. It uses SQLite as its default storage mechanism, which allows for efficient querying and data management[1][7].
Relational Data: If your data has complex relationships, such as one-to-many or many-to-many relationships, Core Data is the appropriate choice. It allows you to define entities and relationships between them, making it easier to manage relational data[1][9].
Advanced Features: Core Data provides advanced features like data validation, undo and redo functionality, and lazy loading of data. These features are beneficial for applications that require robust data management capabilities[1][9].
Performance: Core Data fetches only the data it needs to fulfill a request, which can improve performance for large data sets. It also supports efficient data caching and indexing[1][9].
Complex Queries: Core Data allows for complex querying and filtering of data using predicates, which can be more efficient than manually filtering data in memory[1][9].
When to Use NSUserDefaults
NSUserDefaults is a simpler key-value storage system designed for storing small amounts of data. It is suitable for:
User Preferences and Settings: NSUserDefaults is ideal for storing user preferences, settings, and other small pieces of data that need to persist between app launches. Examples include theme settings, user preferences, and simple configuration options[1][3][4].
Simple Data Types: It is designed to store simple data types such as Bool, Int, Float, Double, String, URL, arrays, and dictionaries. It is not suitable for storing large or complex data structures[3][11].
Quick Access: NSUserDefaults keeps its data in memory for quick access, making it efficient for small, frequently accessed pieces of data[1][3][11].
