How can previous messages be displayed to the user if the network is unavailable?

To display previous messages to the user when there is no network on iOS, you need to implement local message caching. This can be done by:

• Saving received messages in a local database, such as Core Data or Realm.
• When loading the chat, first load messages from the local storage.
• When there is no network, display these local data.

Example of using Core Data to load messages:

func fetchCachedMessages() -> [Message] {
    let fetchRequest: NSFetchRequest<Message> = Message.fetchRequest()
    fetchRequest.sortDescriptors = [NSSortDescriptor(key: "date", ascending: true)]
    do {
        let messages = try context.fetch(fetchRequest)
        return messages
    } catch {
        print("Error loading messages: \(error)")
        return []
    }
}

Thus, the user always sees the message history, even if the network is unavailable.