Introduction

UnityWebRequest is Unity's modern networking solution for handling HTTP communications. It provides a flexible system for sending requests to web servers and handling responses. This article covers the various HTTP methods and common usage scenarios.

Basic Usage

The fundamental approach involvse creating a UnityWebRequest instance and executing it within a coroutine. Here's a basic example:

using System.Collections;
using UnityEngine;
using UnityEngine.Networking;

public class NetworkManager : MonoBehaviour
{
    void Start()
    {
        StartCoroutine(ExecuteRequest());
    }

    IEnumerator ExecuteRequest()
    {
        Uri targetUri = new Uri("https://www.example.com");
        using (UnityWebRequest request = new UnityWebRequest(targetUri))
        {
            request.timeout = 10;
            yield return request.SendWebRequest();

            if (request.result == UnityWebRequest.Result.ConnectionError || 
                request.result == UnityWebRequest.Result.ProtocolError)
            {
                Debug.LogError($"Request failed: {request.error}");
            }
            else
            {
                Debug.Log("Request completed successfully");
            }
        }
    }
}

GET Request

The GET method retrieves data from a specified URL. Unity provides a convenient helper method for this:

using System.Collections;
using UnityEngine;
using UnityEngine.Networking;

public class DataFetcher : MonoBehaviour
{
    void Start()
    {
        StartCoroutine(FetchData());
    }

    IEnumerator FetchData()
    {
        UnityWebRequest request = UnityWebRequest.Get("https://api.example.com/data");
        
        yield return request.SendWebRequest();

        if (request.result == UnityWebRequest.Result.Success)
        {
            Debug.Log($"Data retrieved. Size: {request.downloadedBytes} bytes");
            string response = request.downloadHandler.text;
            Debug.Log($"Response: {response}");
        }
        else
        {
            Debug.LogError($"Error: {request.error}");
        }
    }
}

POST Request

POST requests send form data to the server, commonly used for user authentication and data submission:

using System.Collections;
using UnityEngine;
using UnityEngine.Networking;

public class AuthService : MonoBehaviour
{
    void Start()
    {
        StartCoroutine(Login("user@example.com", "password123"));
    }

    IEnumerator Login(string username, string password)
    {
        WWWForm formData = new WWWForm();
        formData.AddField("username", username);
        formData.AddField("password", password);
        formData.AddField("remember", "true");

        UnityWebRequest request = UnityWebRequest.Post("https://api.example.com/auth/login", formData);

        yield return request.SendWebRequest();

        if (request.result == UnityWebRequest.Result.Success)
        {
            Debug.Log("Login successful");
            string token = request.downloadHandler.text;
            // Process token here
        }
        else
        {
            Debug.LogError($"Login failed: {request.error}");
        }
    }
}

PUT Request

PUT requests upload data to the server, useful for file uploads or data updates:

using System.Collections;
using UnityEngine;
using UnityEngine.Networking;

public class UploadManager : MonoBehaviour
{
    void Start()
    {
        StartCoroutine(UploadData());
    }

    IEnumerator UploadData()
    {
        string payload = "Sample upload content";
        byte[] bodyData = System.Text.Encoding.UTF8.GetBytes(payload);

        using (UnityWebRequest request = UnityWebRequest.Put("https://api.example.com/upload", bodyData))
        {
            yield return request.SendWebRequest();

            if (request.result == UnityWebRequest.Result.Success)
            {
                Debug.Log("Upload completed");
            }
            else
            {
                Debug.LogError($"Upload error: {request.error}");
            }
        }
    }
}

HEAD Request

HEAD requests retrieve headers without downloading the full body. This is useful for checking file sizes or availability:

using System.Collections;
using UnityEngine;
using UnityEngine.Networking;

public class ResourceChecker : MonoBehaviour
{
    void Start()
    {
        StartCoroutine(CheckResource());
    }

    IEnumerator CheckResource()
    {
        UnityWebRequest request = UnityWebRequest.Head("https://cdn.example.com/resource.zip");
        
        yield return request.SendWebRequest();

        if (request.result == UnityWebRequest.Result.Success)
        {
            Debug.Log("Resource available");
            
            // Retrieve content length from headers
            string contentLength = request.GetResponseHeader("Content-Length");
            if (!string.IsNullOrEmpty(contentLength))
            {
                long fileSize = long.Parse(contentLength);
                Debug.Log($"File size: {fileSize} bytes");
            }
            
            string contentType = request.GetResponseHeader("Content-Type");
            Debug.Log($"Content-Type: {contentType}");
        }
        else
        {
            Debug.LogError($"Check failed: {request.error}");
        }
    }
}

Download with Progress

For large files, implementing progress tracking provides better user feedback:

using System.Collections;
using System.IO;
using UnityEngine;
using UnityEngine.Networking;
using UnityEngine.UI;

public class DownloadController : MonoBehaviour
{
    public Slider progressSlider;
    public Text percentageText;
    
    private string downloadUrl = "https://example.com/large-file.zip";
    private string savePath;

    void Start()
    {
        savePath = Path.Combine(Application.persistentDataPath, "Downloads");
        if (!Directory.Exists(savePath))
        {
            Directory.CreateDirectory(savePath);
        }
        
        progressSlider.value = 0;
        percentageText.text = "0%";
        
        StartCoroutine(DownloadFile());
    }

    IEnumerator DownloadFile()
    {
        UnityWebRequest request = UnityWebRequest.Get(downloadUrl);
        
        request.SendWebRequest();

        while (!request.isDone)
        {
            progressSlider.value = request.downloadProgress;
            percentageText.text = $"{Mathf.FloorToInt(request.downloadProgress * 100)}%";
            yield return null;
        }

        if (request.result == UnityWebRequest.Result.Success)
        {
            progressSlider.value = 1.0f;
            percentageText.text = "100%";
            
            string fileName = Path.GetFileName(downloadUrl);
            string fullPath = Path.Combine(savePath, fileName);
            
            SaveToFile(fullPath, request.downloadHandler.data);
            
            Debug.Log($"Download complete: {fullPath}");
        }
        else
        {
            Debug.LogError($"Download failed: {request.error}");
        }
    }

    void SaveToFile(string path, byte[] data)
    {
        File.WriteAllBytes(path, data);
    }
}

Important Notes

• Always use UnityWebRequest.Result instead of checking isNetworkError and isHttpError separately for Unity 2020+
• Use the using statement or manually dispose of requests to prevent memory leaks
• Set appropriate timeout values for network operations
• Use Application.persistentDataPath for file storage on mobile devices
• Always handle both network errors and HTTP error responses