Write me a script in Unity that uses JSON to save and read user data (names, passwords, etc.) in C#.

Sure! Here's an example script that demonstrates how to use JSON to save and read user data in Unity using C#:

using UnityEngine;
using System.IO;
using System.Collections.Generic;

public class UserDataManager : MonoBehaviour
{
    private string filePath;
    private Dictionary<string, string> userData;

    void Start()
    {
        filePath = Application.persistentDataPath + "/userdata.json";
        LoadUserData();
    }

    public void SaveUserData(string username, string password)
    {
        if (userData.ContainsKey(username))
        {
            userData[username] = password;
        }
        else
        {
            userData.Add(username, password);
        }

        string dataAsJson = JsonUtility.ToJson(userData);
        File.WriteAllText(filePath, dataAsJson);
    }

    public bool VerifyUserData(string username, string password)
    {
        if (userData.ContainsKey(username) && userData[username] == password)
        {
            return true;
        }

        return false;
    }

    private void LoadUserData()
    {
        if (File.Exists(filePath))
        {
            string dataAsJson = File.ReadAllText(filePath);
            userData = JsonUtility.FromJson<Dictionary<string, string>>(dataAsJson);
        }
        else
        {
            userData = new Dictionary<string, string>();
        }
    }
}

Here's how to use this script:

1. Attach this script to a GameObject in your Unity scene.
2. Call `SaveUserData` to save a user's data. Pass in the user's username and password as parameters.
3. Call `VerifyUserData` to check if a user's data is valid. Pass in the user's username and password as parameters.

This script uses a dictionary to store user data, where the keys are usernames and the values are passwords. When `SaveUserData` is called, it checks if the username already exists in the dictionary. If it does, it updates the password. If it doesn't, it adds a new key-value pair to the dictionary. Then it serializes the dictionary to JSON and writes it to a file on disk.

When `VerifyUserData` is called, it checks if the username exists in the dictionary and if the password matches the value associated with that username.

The `LoadUserData` function is called in `Start` to read the saved user data from disk and deserialize it into the dictionary. If the file doesn't exist, it creates a new empty dictionary.