Using OpenFeint for iPhone Game Highscore Server without Full-Blown App

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Introduction

OpenFeint was a popular social gaming network that allowed developers to easily integrate leaderboards and other social features into their games. While the full-blown app is no longer available, its API and data storage services are still accessible for use in third-party applications.

In this post, we will explore how to use OpenFeint as a highscore server for an iPhone game without deploying the entire OpenFeint app within your own application. We’ll cover the setup process, data structure, API usage, and potential pitfalls to avoid.

Background

OpenFeint was acquired by Gree in 2011 and eventually shut down its services in December 2013. However, its legacy lives on through the existing API documentation, which remains available for reference. The OpenFeint API allows developers to create highscores, retrieve leaderboards, and perform other social actions without having to build a full-fledged app.

Technical Requirements

To use OpenFeint as a highscore server, you will need:

An iPhone game built using Xcode
A basic understanding of Objective-C or Swift (for Xcode)
Familiarity with JSON data formats
Internet connectivity for API requests

Setting Up the Server

To use OpenFeint’s services, you’ll first need to sign up for an account on their developer portal. Once you have your account set up, you can retrieve an API key that will be used to authenticate your requests.

Authentication and Authorization

OpenFeint uses a token-based authentication system. When you create a new highscore or update an existing one, the OpenFeint API expects you to provide a valid API key as part of the request headers.

Here’s an example of how to use the HttpClient class in Objective-C to send a POST request with your API key:

#import <Foundation/Foundation.h>

@interface OpenFeintService : NSObject

+ (NSString *) authenticateWithApiKey:(NSString *) apiKey;

@end

@implementation OpenFeintService

+ (NSString *)authenticateWithApiKey:(NSString *)apiKey {
    // Create the headers dictionary
    NSDictionary *headers = @{
        @"Authorization": [NSString stringWithFormat:@"Bearer %@", apiKey],
        @"Content-Type": @"application/json"
    };

    // Send the POST request to create a new highscore
    NSURLRequest *request = [NSURLRequest requestWithURL:@"https://api.openfeint.com/1.0/highscores" headers:headers body:nil];

    // Parse the response to extract the API key
    NSData *responseData = [NSData dataWithContentsOfURL:[NSURL URLByAppendingPathComponent:@"highscore_response"]];
    NSDictionary *responseDictionary = [NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableContainers error:nil];
    return [[responseDictionary objectForKey:@"api_key"] stringValue];
}

@end

Similarly, you can use the HttpClient class in Swift to send a POST request with your API key:

import Foundation

class OpenFeintService {
    static func authenticateWithApiKey(_ apiKey: String) -> String {
        // Create the headers dictionary
        let headers = ["Authorization": "Bearer \(apiKey)", "Content-Type": "application/json"]
        
        // Send the POST request to create a new highscore
        var request = URLRequest(url: URL(string: "https://api.openfeint.com/1.0/highscores")!, cachePolicy: .useProtocolCachePolicy, timeoutInterval: 10)
        request.httpMethod = "POST"
        request.httpBody = nil
        
        // Parse the response to extract the API key
        let data = try! Data(contentsOf: URL(string: "highscore_response")!)
        do {
            let responseDictionary = try JSONSerialization.jsonObject(with: data, options: .allowFragments)
            return responseDictionary["api_key"] as? String
        } catch {
            print("Error parsing response: \(error)")
            return nil
        }
    }
}

Data Structure and API Usage

Once you’ve authenticated your requests, you can start using the OpenFeint API to create highscores. The API expects a JSON payload with the following structure:

{
    "user_id": 1,
    "game_id": 2,
    "score": 1000
}

Here’s an example of how to use the OpenFeintService class in Objective-C to create a new highscore:

#import <Foundation/Foundation.h>

@interface OpenFeintService : NSObject

+ (void)createHighScoreWithUserId:(NSInteger)userId gameId:(NSInteger)gameId score:(NSInteger)score;

@end

@implementation OpenFeintService

+ (void)createHighScoreWithUserId:(NSInteger)userId gameId:(NSInteger)gameId score:(NSInteger)score {
    // Create the highscore payload
    NSDictionary *highscorePayload = @{
        @"user_id": @(userId),
        @"game_id": @(gameId),
        @"score": @(score)
    };

    // Send the POST request to create a new highscore
    NSURLRequest *request = [NSURLRequest requestWithURL:@"https://api.openfeint.com/1.0/highscores" headers:@{ "Authorization": [[OpenFeintService authenticateWithApiKey:@"YOUR_API_KEY"] stringValue] } body:[NSJSONSerialization dataWithJSONObject:highscorePayload options:NSJSONWritingPrettyPrinted error:nil]];
    [NSURLRequest sendSynchronousRequest:request returningResponse:nil error:nil];
}

@end

Similarly, you can use the OpenFeintService class in Swift to create a new highscore:

import Foundation

class OpenFeintService {
    static func createHighScoreWithUserId(_ userId: Int, gameId: Int, score: Int) {
        // Create the highscore payload
        let highscorePayload = ["user_id": userId, "game_id": gameId, "score": score]
        
        // Send the POST request to create a new highscore
        guard let data = try? JSONSerialization.jsonObject(with: highscorePayload, options: .allowFragments).data() else {
            print("Error creating highscore")
            return
        }
        var request = URLRequest(url: URL(string: "https://api.openfeint.com/1.0/highscores")!, cachePolicy: .useProtocolCachePolicy, timeoutInterval: 10)
        request.httpMethod = "POST"
        request.httpBody = data
        
        // Parse the response to extract the API key
        let dataResponse = try? Data(contentsOf: URL(string: "highscore_response")!)
        guard let responseDictionary = try? JSONSerialization.jsonObject(with: dataResponse, options: .allowFragments) else {
            print("Error parsing response")
            return
        }
    }
}

Potential Pitfalls to Avoid

While using OpenFeint as a highscore server can be a convenient solution for your iPhone game, there are some potential pitfalls to watch out for:

Data Integrity: Since you’re relying on the OpenFeint API to store and retrieve data, ensure that you understand how their system handles data integrity. For example, they use SSL encryption for secure transactions, but it’s still possible for an attacker to manipulate data.
Server Latency: If your game requires real-time updates or leaderboards, be aware that OpenFeint’s server latency might impact the user experience. You may need to implement caching mechanisms or use a more robust API to mitigate this issue.
API Limitations: Be mindful of OpenFeint’s API limitations and usage restrictions. They have rate limits on the number of requests you can make per day, so ensure that your implementation doesn’t exceed these limits.

Conclusion

In conclusion, using OpenFeint as a highscore server for your iPhone game can be a convenient solution. By understanding how their API works, implementing secure authentication mechanisms, and being aware of potential pitfalls, you can build a reliable and scalable leaderboards system for your game.

Last modified on 2023-10-24