Question

I’m wondering if there is a possibility when you upload your highscore you can compare your score with the one of your friends (if simpler, only selected contacts)?
And if so, could someone point me in the right direction, how to do it? I did not find anything useful about this on google.
As far as I pressume it should be possible, because apps like WhatsApp also let you choose specific contacts you want to send a message.
Related to that: Can I just use a/the cloud for uploading highscore or should I use my webspace?

Answer 1

I am not answering this specific to iOS/etc.

What you would typically do is expose a REST (or POX/POJSON – plain old XML or plain old JSON) service on your website that your application communicates with – it would be responsible for negotiating friendships, uploading high scores and retrieving high scores. This would either hit a database under your control or it would connect to a cloud server; there is no problem with either approach (Azure is a good option if you want to apply my SQL concepts).

Inside your database you would maintain a list of friends – this is a very simple structure to set up. Essentially you want two tables that look like the following:

CREATE TABLE [UserAccount]
(
  [ID] BIGINT IDENTITY(1,1) PRIMARY KEY,
  [Name] NVARCHAR(255),
)

CREATE TABLE [Friendship]
(
  [User1] BIGINT, -- Primary key, FK to [UserAccount].[ID]
  [User2] BIGINT, -- Primary key, FK to [UserAccount].[ID]
)

This would allow you to indicate friendships along the lines of:

User: ID = 1, Name = Joe
User: ID = 2, Name = Fred
Friendship: User1 = 1, User2 = 2
Friendship: User1 = 2, User1 = 1

You can then query friends using the following query:

SELECT [F1].[User2] AS [ID] FROM [Friendship] AS [F1]
 WHERE [F1].[User1] = @CurrentUser
   -- Check for symmetric relationship.
   AND EXISTS
       ( SELECT 1 FROM [Friendship] AS [F2]
          WHERE [F2].[User2] = [F1].[User1] AND [F2].[User1] = [F1].[User2] );

You could make that a TVF (Table Value Function) if your SQL variant supports them. Next you would create a high score table and a table to map it to users.

 CREATE TABLE [Highscore]
 {
   [ID] BIGINT IDENTITY(1,1) PRIMARY KEY,
   [Score] INT,
 }

 CREATE TABLE [UserHighscore]
 {
   [UserID] BIGINT, -- Primary key, FK to User.ID
   [HighscoreID] BIGINT, -- Primary key, FK to Highscore.ID
 }

Some sample data for this would be:

 -- In this game you can only score over 9000!
 Highscore: ID = 1, Score = 9001
 Highscore: ID = 2, Score = 9005
 Highscore: ID = 3, Score = 9008
 UserHighscore: UserID = 1, HighscoreID = 1
 UserHighscore: UserID = 1, HighscoreID = 2
 UserHighscore: UserID = 2, HighscoreID = 3

You can then query for your friends’ highscores:

SELECT TOP(10) [U].[Name], [H].[Score] FROM [Friendship] AS [F1]
 LEFT INNER JOIN [User] AS [U] ON [U].[ID] = [F1].[User2]
 LEFT INNER JOIN [HighscoreUser] AS [HU] ON [HU].[UserID] = [F1].[User2]
 LEFT INNER JOIN [Highscore] AS [H] ON [H].[ID] = [HU].[UserID]
 WHERE [F1].[User1] = @CurrentUser
   -- Check for symmetric relationship.
   AND EXISTS
       ( SELECT 1 FROM [Friendship] AS [F2]
          WHERE [F2].[User2] = [F1].[User1] AND [F2].[User1] = [F1].[User2] )
 ORDER BY [H].[Score] DESC;

That query would give the top 10 score your friends; giving you their name and score.