What problem does reactive programming solve?

Reactive programming addresses the problem of managing changing data streams over time. It simplifies working with asynchronous events and data streams by allowing declarative descriptions of how the system responds to changes. This makes the codebase more predictable, readable, and maintainable, especially in applications with many interactive elements and asynchronous operations (network requests, user input, notifications, etc.).

Main problems solved by reactive programming:

1. Complexity of asynchronous code: Eliminates "callback hell" and improves readability compared to traditional approaches based on delegates, notifications, or completion handlers.
2. State management: Easily tracks and reacts to changes in state across different parts of the application.
3. Error handling: Provides a standardized mechanism for handling errors in asynchronous streams.
4. Operation composition: Facilitates merging, transforming, and filtering streams of events and data.
5. Backpressure: In some implementations (Swift Combine Foundation, Rx frameworks), helps manage situations where the data source generates events faster than the subscriber can process them.

Examples of use in iOS:

• Responding to user input (e.g., text changes in UITextField).
• Monitoring network status changes.
• Handling API responses.
• Binding UI elements to data (Data Binding).
• Reacting to changes in databases (Core Data, Realm).

Frameworks used:

• Swift Combine Foundation
• RxSwift
• ReactiveCocoa