Explain what the Core Data framework is and how it is used to manage data in iOS applications.

Core Data is an Apple framework for managing the data model in iOS and macOS applications. It provides an object-oriented layer over the data store, allowing you to work with data as objects.

Main features of Core Data:

• Managing the lifecycle of objects (creation, reading, updating, deletion).
• Support for complex relationships between objects.
• Caching and query optimization.
• Support for various store types (SQLite, binary files, in-memory).
• Automatic change tracking and notifications.

Using Core Data in an application typically involves:

1. Defining a data model (.xcdatamodeld) with entities and their attributes.
2. Creating an NSManagedObjectContext to work with objects.
3. Performing fetch requests using NSFetchRequest.
4. Saving changes in the context.

Example of creating and saving an object:

let context = persistentContainer.viewContext
let newUser = NSEntityDescription.insertNewObject(forEntityName: "User", into: context)
newUser.setValue("Ivan", forKey: "name")

do {
    try context.save()
} catch {
    print("Save error: \(error)")
}

Core Data simplifies working with data, especially when complex logic and performance are required.