File-based save system in Unity

Introduction

A file-based save system lets your game remember player progress by saving data to a file on the device. This way, players can continue where they left off even after closing the game.

You want to save player scores or levels between game sessions.

You need to store player settings like volume or controls.

You want to save game progress locally without using online servers.

You want to load saved data when the game starts.

You want to backup or export player data easily.

Syntax

Unity

using System.IO;
using UnityEngine;

public class SaveSystem
{
    private string filePath = Application.persistentDataPath + "/savefile.json";

    public void Save(string data)
    {
        File.WriteAllText(filePath, data);
    }

    public string Load()
    {
        if (File.Exists(filePath))
        {
            return File.ReadAllText(filePath);
        }
        return null;
    }
}

Use Application.persistentDataPath to get a safe place to save files on any device.

Use File.WriteAllText to save text data and File.ReadAllText to load it back.

Examples

Saves the text "Hello World" to the file and then reads it back into a string.

Unity

File.WriteAllText(filePath, "Hello World");
string content = File.ReadAllText(filePath);

Checks if the save file exists before trying to read it to avoid errors.

Unity

string path = Application.persistentDataPath + "/playerdata.json";
if (File.Exists(path))
{
    string json = File.ReadAllText(path);
}

Sample Program

This program saves a player's level and health to a JSON file and then loads it back, printing the values to the Unity console.

Unity

using System.IO;
using UnityEngine;

[System.Serializable]
public class PlayerData
{
    public int level;
    public float health;
}

public class SaveSystemExample : MonoBehaviour
{
    private string filePath;

    void Start()
    {
        filePath = Application.persistentDataPath + "/playerdata.json";

        // Create some data
        PlayerData data = new PlayerData { level = 5, health = 75.5f };

        // Convert to JSON
        string json = JsonUtility.ToJson(data);

        // Save to file
        File.WriteAllText(filePath, json);

        // Load from file
        if (File.Exists(filePath))
        {
            string loadedJson = File.ReadAllText(filePath);
            PlayerData loadedData = JsonUtility.FromJson<PlayerData>(loadedJson);
            Debug.Log($"Loaded Level: {loadedData.level}, Health: {loadedData.health}");
        }
    }
}

Important Notes

Always check if the file exists before loading to avoid errors.

Use JSON format to save complex data like player stats in a readable way.

Files saved in Application.persistentDataPath stay between game sessions and app updates.

Summary

A file-based save system stores game data on the device so progress is not lost.

Use File.WriteAllText and File.ReadAllText with Application.persistentDataPath for safe saving and loading.

JSON is a simple format to save and load structured data like player stats.