Return array from foreach

I have a problem with this class in the administrative area of wordpress.

I would like to return the value of foreach, but unfortunately returns an empty variable!

If I use the print_r inside the foreach everything works!

Can you help me to understand where I wrong?

This is my code:

class MyClass{   
     function __construct(){
          add_action( 'admin_init',array( $this, 'getPostType' ) );
     }
     function getPostType(){
          $args = array(
               'public'   => true,
               '_builtin' => false
          );

          $output = 'names';
          $operator = 'and';

          $post_types = get_post_types( $args, $output, $operator );
          $types = array();

          foreach($post_types as $postype){
              $types[] = array(
                  'value' => $postype,
              );
              return $types;
          }   
     }
}

$var = new MyClass();
foreach($var->getPostType() as $type){
   echo $type;
}

Thanks in advance and sorry for my bad English!

Change

class MyClass{   
     function __construct(){
          add_action( 'admin_init',array( $this, 'getPostType' ) );
     }
     function getPostType(){
          $args = array(
               'public'   => true,
               '_builtin' => false
          );

          $output = 'names';
          $operator = 'and';

          $post_types = get_post_types( $args, $output, $operator );
          $types = array();

          foreach($post_types as $postype){
              $types[] = array(
                  'value' => $postype,
              );
          } return $types;
     }
}

$var = new MyClass();
print_r($var->getPostType());

I get this: Array ( )

$post_types return a correct value.

Debug:

class MyClass{   
     function __construct(){
          add_action( 'admin_init',array( $this, 'getPostType' ) );
     }
     function getPostType(){
          $args = array(
               'public'   => true,
               '_builtin' => false
          );

          $output = 'names';
          $operator = 'and';

          $post_types = get_post_types( $args, $output, $operator );
          var_dump($post_types); // array(1) { ["book"]=> string(4) "book" } 

          $types = array();
          foreach($post_types as $postype){
              $types[] = array(
                  'value' => $postype,
              );
              var_dump($postype); // string(4) "book" 
          } return $types;
     }
}