I need you to write Swift code for a SwiftUI feature using The Composable Architecture (TCA) pattern - https://github.com/pointfreeco/swift-composable-architecture that includes:
* A TextField where the user can input a topic.
* A Button that, when tapped, triggers an action to load questions related to the entered topic.
* A List that displays all the questions fetched from a mock API based on the topic.
* A Loading Spinner (ActivityIndicator) that appears while the questions are being fetched.
* If no questions are found, the list should appear empty.

Use The Composable Architecture (TCA) structure, ensuring that the code is:
* Modular, clean, and testable.
* Built with the following components:
  * View: A SwiftUI view that displays the text field, button, list of questions, and loading spinner.
  * Feature: A Struct that contains the reducer logic, handles how actions modify the state, including setting loading state, handling results, and updating the view accordingly.
    * Within the Feature struct
       * State: Holds the user's topic input, the loading state, the fetched questions, and a flag for handling empty results.
       * Action: Triggers for text input changes, button taps, starting the API call, receiving the API response, and finishing loading.
  * APIClient: Simulates a simple API call using a delay. This should be a dependency that can be used by the Feature

Ensure that:
* If the API call returns no questions, display an empty list with no error message.
* While the API call is in progress, show a loading spinner in place of the list.
* You provide comments to explain each part of the architecture.
* The code is concise, avoiding unnecessary complexity.
* Do not include unit tests in the code. Return the complete code as a single file that can be copied directly and run in an existing XCode project

As a Principle iOS Engineer I want you to help me write functional Swift code that compiles.

Architecture Pattern: The Composable Architecture - https://github.com/pointfreeco/swift-composable-architecture

Requirements: 
1. Create a Swift UI View that has one text field to enter a topic, and one button to load questions using the text entered by the user.

Assumptions: Assume I already have an XCode project created and that I have already imported The Composable Architecture dependency in my project

Output: Firstly Provide the Names and functions of the entities that will be needed to build the feature

Make the Reducer functionality be part of a struct or class?

modify the code above to move the QuestionState QuestionAction and QuestionEnvironment inside the QuestionFeature

Actually please take the Environment out of the QuestionFeature, and make it a separate struct called QuestionAPI

Now please provide the code in a single file containing the QuestionView, the QuestionFeature and the QuestionAPI

You will act as an expert Swift developer specializing in The Composable Architecture (TCA) pattern - https://github.com/pointfreeco/swift-composable-architecture 

I need you to write Swift code for a SwiftUI feature using TCA that includes:
* A TextField where the user can input a topic.
* A Button that, when tapped, triggers an action to load questions related to the entered topic.
* A List that displays all the questions fetched from a mock API based on the topic.
* A Loading Spinner (ActivityIndicator) that appears while the questions are being fetched.
* If no questions are found, the list should appear empty.

Use The Composable Architecture (TCA) structure, ensuring that the code is:
* Modular, clean, and testable.
* Built with the following components:
  * View: A SwiftUI view that displays the text field, button, list of questions, and loading spinner.
  * Feature: A Struct that contains the reducer logic, handles how actions modify the state, including setting loading state, handling results, and updating the view accordingly.
    * Within the Feature struct
       * State: Holds the user's topic input, the loading state, the fetched questions, and a flag for handling empty results.
       * Action: Triggers for text input changes, button taps, starting the API call, receiving the API response, and finishing loading.
  * APIClient: Simulates a simple API call using a delay. This should be a dependency that can be used by the Feature

Ensure that:
* If the API call returns no questions, display an empty list with no error message.
* While the API call is in progress, show a loading spinner in place of the list.
* You provide comments to explain each part of the architecture.
* The code is concise, avoiding unnecessary complexity.
* Do not include unit tests in the code. Return the complete code as a single file that can be copied directly and run in an existing XCode project

You will act as an expert Swift developer specializing in The Composable Architecture (TCA) pattern - https://github.com/pointfreeco/swift-composable-architecture 

I need you to write Swift code for a SwiftUI feature using TCA that includes:
* A TextField where the user can input a topic.
* A Button that, when tapped, triggers an action to load questions related to the entered topic.
* A List that displays all the questions fetched from a mock API based on the topic.
* A Loading Spinner (ActivityIndicator) that appears while the questions are being fetched.
* If no questions are found, the list should appear empty.

Use The Composable Architecture (TCA) structure, ensuring that the code is:
* Modular, clean, and testable.
* Has a SwiftUI View called 'TopicInputView' that has one text field to enter a topic, and one button to load questions using the text entered by the user.
* The State of the view should be maintained by a TopicInputFeature Reducer, which is a struct that contains the reducer logic, handles how actions modify the state, including setting loading state, handling results, and updating the view accordingly.
  * Within the TopicInputFeature struct
     * State: Holds the user's topic input, the loading state, the fetched questions, and a flag for handling empty results.
     * Action: Triggers for text input changes, button taps, starting the API call, receiving the API response, and finishing loading.
* The API call should be made by a TriviaAPIClient that can be used by the Reducer as a dependency

Ensure that:
* If the API call returns no questions, display an empty list with no error message.
* While the API call is in progress, show a loading spinner in place of the list.
* You provide comments to explain each part of the architecture.
* The code is concise, avoiding unnecessary complexity.
* Do not include unit tests in the code. Return the complete code as a single file that can be copied directly and run in an existing XCode project

Can you modify the code to put the reducer functionality inside a struct called TopicInputFeature