Getting Phonegap app to communicate to Codeigniter Server in Android and Access-Control-Allow-Origin error - codeigniter

Question

I am extremely new to using phonegap,codeigniter and jQuery Mobile (My first project) and have currently created an app with jQuery Mobile on the Client side and on the Server side I used the Codeigniter framework to create a RESTful API. Now when I am developing locally the app with in the browser (not yet using phonegap) communicates just fine with the API and no problems occur.
I placed the Codeigniter API on a server yesterday and I am now encountering 2 problems:
The App which was built using jQuery Mobile keeps getting the
following error:
Origin localhost is not allowed by Access-Control-Allow-Origin.
Now I have done some reading up and most people say to use jsonp instead of json and also to use the following on the Server Side:
$CI->output->set_header("Access-Control-Allow-Origin: *");
$CI->output->set_header("Access-Control-Expose-Headers: Access-Control-Allow-Origin");
$CI->output->set_status_header(200);
$CI->output->set_content_type('application/json');
Now my problem is I'm not entirely sure which one is used to fix the problem, weather it is both that need to be implemented etc. If they need to be fixed, how is it done? Is there a place that is well documented that can teach me how to deal with this problem, preferably I would like some where to read up on so I can learn?
The second problem is when I place the jQuery Mobile app into
phonegap and build it for Android. The app fails to get the
data from the server. Now is the reason for this because of the cross
domain error above or is this problem different? I also did some
reading up in this section as well and to my Android config.xml I
added the following code:
But I'm I still can't pull anything from the server. Like I said I'm a bit of a newbie but would really appreciate some help in this matter. Also I am aware that I haven't posted code but based on the comments I'll post which ever code the community needs to help solve this problem, just simply specify which code. Thank you for the help in advance!

Answer 1

About the Access-Control-Allow-Origin problem, I faced the same error and solved by placing this line <?php header('Access-Control-Allow-Origin: *'); ?> in the index.php which is in the root of the project.

Answer 2

This question hasn't been answered 100% but for now thanks to the help of #Niloy Saha, to fix the Access-Control-Allow-Origin error with with the Codeigniter RESTful frame work simply go to your controller in the Controller folder and right at the top paste;
header('Access-Control-Allow-Origin: *');
This then should allow you to communicate from the browser to the server and be able to get a response. After a good for hours of trying I managed to fix my problem. With in the Android project in the res/xml folder there is a file called config.xml. In that file be sure to have the following code:
<access origin="http://10.0.2.2*" subdomains="true"/>
and also make sure you have the following:
<uses-permission android:name="android.permission.INTERNET" />
in your AndroidManifest.xml. For me that seemed to get everything to work

Answer 3

I did similar thing as yours, Zend FW with API on server and jQuery Mobile App.
I've used JSONP, didn't use any Access-Control-Allow-Origin headers.
I have a method in my controller:
function returnData($data) {
header('Content-type: text/javascript');
echo $_GET['callback']. '('. json_encode($data). ')';
die();
}
At the end of API call i use it to return data.
Getting data in jQuery:
$.ajax({
dataType: "jsonp",
url: url,
data: {someparam: 'value'},
success: function(data) { /* ur data is here */ }
});