Describe how you will solve the problem of caching the car price: data structure, synchronization, update.

For caching the car price, I would use the following strategy:

• Data structure:

  • In-memory cache (e.g., dictionary or NSCache), where the key is the unique car identifier, and the value is an object with the price and metadata (last update time).

• Synchronization:

  • If the application is multithreaded, access to the cache should be protected using thread-safe mechanisms (e.g., DispatchQueue with barriers or NSLock).

• Updating:

  • When requesting the price, first check the cache:
    • If the price exists and is not outdated (e.g., updated less than N minutes ago), return it from the cache.
    • If not or outdated — make a request to the server, update the cache, and return the new price.
  • You can implement background cache updates to keep data fresh.

This approach ensures quick access to frequently requested prices and minimizes network load while maintaining data relevance.