Displaying The Scores Table
As mentioned before, we will be displaying a table on a webpage. The url that the webview will access will be something like this
http://icodeblog.com/ws/get_scores.php?sort=score%20DESC
There are quite a few parameters that can be used with my script that will determine how the table will be displayed. The parameters and their descriptions are in the table below:
| Variable | Description |
|---|---|
| type | This value will determine what data the table will display. The possible values for it are global, device, and name. Global will simply show the global high scores list containing all of the users. Device is specific to the calling users device. It will only display high scores for a given udid. Finally, we have name, which will only display high scores for a given username. |
| offset | Used for paging the SQL results. It will be the first parameter in the ORDER BY clause of the SQL select statement. Ex: An offset of 10 will tell the system to show records starting with the 10th. |
| count | Used for paging the SQL results. It will be the second parameter in the ORDER BY clause of the SQL select statement. This is basically the number of results to show in the table. |
| sort | Tells the table how to sort. If this isn’t specified, the sorting is default set to “score DESC”. This will order by scores from highest to lowest. |
| udid | The UDID of the device viewing the leaderboard. This variable is required if you specify type=device |
| name | The name of the device viewing the leaderboard. This variable is required if you specify type=name |
As you can see, you have quite a bit of control over how the results get displayed. You may want to offer multiple high score views to your user (global, personal, etc…). You can also fancy this up quite a bit and give the users the ability to view the high scores of other users on the list.
Here is the code for get_scores.php
<?php // get_scores.php /** MySQL database name */ define('DB_NAME', ''); /** MySQL database username */ define('DB_USER', ''); /** MySQL database password */ define('DB_PASSWORD', ''); /** MySQL hostname */ define('DB_HOST', $_ENV{DATABASE_SERVER}); $table = "highscores"; // Initialization $conn = mysql_connect(DB_HOST,DB_USER,DB_PASSWORD); mysql_select_db(DB_NAME, $conn); // Error checking if(!$conn) { die('Could not connect ' . mysql_error()); } $type = isset($_GET['type']) ? $_GET['type'] : "global"; $offset = isset($_GET['offset']) ? $_GET['offset'] : "0"; $count = isset($_GET['count']) ? $_GET['count'] : "10"; $sort = isset($_GET['sort']) ? $_GET['sort'] : "score DESC"; // Localize the GET variables $udid = isset($_GET['udid']) ? $_GET['udid'] : ""; $name = isset($_GET['name']) ? $_GET['name'] : ""; // Protect against sql injections $type = mysql_real_escape_string($type); $offset = mysql_real_escape_string($offset); $count = mysql_real_escape_string($count); $sort = mysql_real_escape_string($sort); $udid = mysql_real_escape_string($udid); $name = mysql_real_escape_string($name); // Build the sql query $sql = "SELECT * FROM $table WHERE "; switch($type) { case "global": $sql .= "1 "; break; case "device": $sql .= "udid = '$udid' "; break; case "name": $sql .= "name = '$name' "; break; } $sql .= "ORDER BY $sort "; $sql .= "LIMIT $offset,$count "; $result = mysql_query($sql,$conn); if(!$result) { die("Error retrieving scores " . mysql_error()); } ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta name="viewport" content="width=320; initial-scale=1.0; maximum-scale=1.0; user-scalable=0;"/> </head> <body> <?php // Display the table echo '<table style="width:100%"> <thead> <tr> <th>Name</th> <th>Score</th> </tr> </thead> <tbody>'; while ($row = mysql_fetch_object($result)) { echo '<tr> <td> '.$row->name.' </td> <td> '.$row->score.' </td> </tr>'; } echo '</tbody> </table>'; mysql_free_result($result); mysql_close($conn); ?> </body> </html>
After initialization, we build the SQL query based on the parameters that were specified. This will determine what data will get displayed. Notice that after the code to query the database, there is some HTML. This is because we want to output a full HTML page for our table. You can use this opportunity to ad things such as styling, images, and advertising.
Within the body, we simply loop over the results returned from MYSQL and output the score data. And that’s it! You now have a fully functional high score server.
With our server complete, there are only two things left to do: submit score data in our iphone application and display the leaderboard.
18 Comments
No, thank YOU very much!
I was thinking on implementing something like this in my game and you just made my work easier.
Thanks, excellent, I’m sure I’ll use it at some point.
Hi! Thanks very much for the tutorial!
I have one question about getting highscrores. How I can get the scrores from the php page to the iphone sdk labels and textboxes e.t.c? I don’t want to use UIWebView.
Please answer to the mail
Very well done ! Love your tuts and I always wonder how to you find time to build them, cz I know how much efforts it takes
For the MySQL,based on my experience I never use FLOAT column type, because I had huge problems with float math on it, I always use DOUBLE instead, which seems to work better.
Also, wouldn’t it be better if the password was sent trough a POST request? Or it was too much code overhead for the simple tutorial ?
Anyhow, I’m always waiting for the new post on your blog, and congrats once more
Marin
@Mikko – You need to make your PHP output XML instead of a table. Then parse this XML in your application into an NSDictionary. From there, you can populate whatever you want with this data.
@Marin – I have never had any issues with FLOAT. But I’m sure you could easily switch it out with DOUBLE. As far as teh POST goes, there are many ways security could be improved. HTTP Basic AUTH would be another way to prevent attacks. I didn’t really want to go too much into it in this tutorial as I wanted to keep things simple and show users how to get a leaderboard up with very little code. Thanks for the suggestion.
Thanks for the code. I was wondering about how to make sure the person can reach the website. It seems that Apple has a framework for checking called SCNetworkReachability and some demo code in the SDK. I’m just adding that here to save people the extra google search.
I cant seem to set up the creat_db.php page I get this error: Could not connect Can’t connect to local MySQL server through socket ‘/tmp/mysql.sock’ (2) and also I am getting confused in xcode. Do you think you could post source code to a sample project that would do everything you described in the tutorial?
Great post. Thanks for this really. I am not a blog reglar blog reader but this blog is truly amazing indeed.
Hi, tnx for this great post. Could you pls place or mail me een .zip with al the files’s?
I build the tutorial but it doesn’t work.
Tnx in advance.
To check for an internet connection, you should use Apple’s Reachability class. Just download it and copy Reachability.h/m to your project. Also, you have to add the SystemConfiguration framework to your project.
https://developer.apple.com/iphone/library/samplecode/Reachability/index.html
Usage:
Reachability* reachability = [Reachability sharedReachability];
[reachability setHostName:@"www.example.com"]; // set your host name here
NetworkStatus remoteHostStatus = [reachability remoteHostStatus];
if(remoteHostStatus == NotReachable) { }
else if (remoteHostStatus == ReachableViaWiFiNetwork) { }
else if (remoteHostStatus == ReachableViaCarrierDataNetwork) { }
Hi, should the submit score method’s return type be NSString *?
Also, if I want to limit the maximum number of entries in the table, how should I modify the code?
Thanks a lot!
I ran into an error when trying to add this to my app:
HighScoresView * hsv = [[HighScoresView alloc] initWithNibName:@”HighScoresView”
bundle:[NSBundle mainBundle]];
[self presentModalViewController:hsv animated:YES];
[hsv release];
The error would say that HighScoresView was undeclared, after a while I got the error to go away. Then I was getting hsv is undeclared and fixed that by adding Controller to the end of each HighScoresView. I was then getting a bad execution error. It seems (I traced through the debugger) that it is not taking the string from my textBox.text (Debugger says it is not a valid CFString. Then when it goes to encode the username it does the same thing and crashes. Do you have any suggestions on how I can fix this? I’ve been puzzle by it for hours now.
-Chris
What if two people enter the same user name? Is there any way to detect if the user name has already been taken? and If so can you explain how one might go about this?
Thanks
Hello,
First I have to say this tutorial has been very helpful, Thanks
I have a few questions though.
I have the leaderboard up and running, and I have it also displaying in my app just fine. A few things that Im running into is when the user clicks the leaderboard button in my app I would like to have them enter there username to submit there high score then have the high scores view controller slides up from the bottom and displays on top of the current view.
Im using your Inserting A UITextField In A UIAlertView, to prompt the user to enter there username. Im not sure how to modify this code, so when the user enters there username and clicks the “OK!” button that it then submits the username and highscore to the leaderbord and closes the UIAlertView and opens the high scores view. And in turn if the user clicks the “Dismiss” button it closes the UIAlertView and opens the high scores view without submitting a score or name.
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@”Enter A Username Here” message:@”this gets covered!” delegate:self cancelButtonTitle:@”Dismiss” otherButtonTitles:@”OK!”, nil];
UITextField *myTextField = [[UITextField alloc] initWithFrame:CGRectMake(12, 45, 260, 25)];
CGAffineTransform myTransform = CGAffineTransformMakeTranslation(0, 60);
[alert setTransform:myTransform];
[myTextField setBackgroundColor:[UIColor whiteColor]];
[alert addSubview:myTextField];
[alert show];
[alert release];
[myTextField release];
The other issue I noticed, is there is nothing stopping someone from submitting multiple high scores, and flooding the leaderboard with just there name and scoe ten times. Is there another “possible simple” PHP script that when submitting a score it does some sort of check, such as checking if the users UDID and username match, and if there score was greater than the one currently on/or in the database then allow them to post it, if not display an alert, or just “Dismiss” the submission and display the high score view.
I know this is asking allot, any help would be great.
Thanks again.
Good Article!
Where is the rest of the tutorial?
I have an online work order system running on MySQL with PHP pages. I want to make an app to retrieve data and post data to the site. I used this tut to create a couple of test pages and can post data and retrieve via Safari. I am a real newbie on iPhone development and could use some help. A tut on posting and retrieving data would be greatly helpful. If there is one somewhere on the web, I can’t find it.
any help on how to identify a user by username/pword instead of udid?
Very Interesting Read! Looking forward to more on this subject Bookmarked this site. Was also curious if anybody could point me to some related material. Thanks in advance.
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[...] In deze stap schrijft men data naar de database. Meestal wordt deze stap niet beschreven. Er staat hooguit: “…en schrijven gaat precies andersom.” Hier vind je een uitstekend voorbeeld hoe dat wel kan met XML. [...]