CoreData vs Realm: What are the differences?

Key Differences between CoreData and Realm

1. Data Model Definition

• In CoreData, the data model is defined using a visual modeling tool called Core Data Model Editor.
• In Realm, the data model is defined using a code-driven approach, where objects and relationships are defined using classes and properties.

2. Data Persistence

• CoreData supports both SQL-based and binary stores for persisting data.
• Realm uses its own embedded object database to persist data, resulting in better performance and simplifying the persistence process.

3. Relationships

• In CoreData, relationships between entities are defined using relationships in the data model.
• In Realm, relationships are defined using properties in the object classes, providing more flexibility and simplicity in managing relationships.

4. Querying and Fetching

• CoreData uses the NSFetchRequest API to fetch and query data, supporting complex queries with filtering, sorting, and grouping options.
• Realm provides a simpler and more intuitive query language to fetch data, with support for filtering, sorting, and grouping operations directly on the object classes.

5. Thread Safety

• CoreData requires explicit handling of multithreading and concurrency by implementing its own thread-safe mechanisms.
• Realm is inherently thread-safe, allowing objects to be directly accessed and modified from multiple threads without the need for additional synchronization.

6. Performance

• CoreData can be slower for complex queries or large data sets due to its reliance on SQL and the overhead of managed objects.
• Realm is known for its superior performance, as it avoids the overhead of managed objects and utilizes an efficient file-based storage system.

In Summary, CoreData and Realm differ in their data model definition approach, data persistence methods, handling of relationships, querying and fetching options, thread safety mechanisms, and performance characteristics.