header('Access-Control-Allow-Origin: *');
header( 'Access-Control-Allow-Headers: Authorization, Content-Type' );

starter.factory('CommonFactory', function($http) {
    var base= 'your api file url';
    return {
      //with POST data method
        login_function: function(user, pass) {
            return $http({
                url: base,
                method: 'POST',
                headers: {'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8'},
                data: postData,
            });
        },

        // With GET data method
        login_function: function(user, pass) {
            return $http({
                url: base+ '?username='+user+'&password='+pass,
                method: 'GET',
                headers: {'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8'},
            });
        },

      }
    });

CommonFactory.login_function($scope.user,$scope.pass)
             .success(function(res) {
                // success handling
                 })
              .error(function(result) {
                //error handling
                 })

PHP Fatal error: uncaught error: call to undefined function utf8_encode()

sudo apt-get install php7.0-xml
sudo service apache2 restart