1. Create an application example, apply the directory apps/example, the directory structure is as follows
   example/appinfo: Contains application metadata and configuration
   example/css: Contains CSS
   example/img: Contains icons and images
   example/js: Contains JavaScript files
   example/lib: PHP class file containing the application
   example/templates: Contains templates
   example/tests: Includes tests

2. Create metadata profiles

   Reference website:

      https://docs.nextcloud.com/server/14/developer_manual/app/init.html
      https://docs.nextcloud.com/server/14/developer_manual/app/info.html

   Create the file example/appinfo/info.xml

   <?xml version="1.0"?>
   <info xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="https://apps.nextcloud.com/schema/apps/info.xsd">
       <id>example</id>
       <name>Example</name>
       <summary>Example summary</summary>
       <description>Example  description</description>
       <version>1.0.0</version>
       <licence>agpl</licence>
       <author>Author</author>
       <category>multimedia</category>
       <bugs>https://github.com/nextcloud/news/issues</bugs>
       <dependencies>
           <nextcloud min-version="10"/>
       </dependencies>
       <!--navigation Navigation entries for applications--> 
       <navigation>
           <name>example</name>
           <route>example.index</route>
           <order>0</order>
       </navigation>
   </info>

   So you can see the example application in the application installation directory.

   
   

3. Create controller example/lib/Controller/ExampleController.php
   https://docs.nextcloud.com/se...

   <?php
   namespace OCA\Example\Controller;
   
   use OCP\AppFramework\Controller;
   use OCP\AppFramework\Http\DataResponse;
   use OCP\IRequest;
   
   class ExampleController extends Controller {
       
       public function __construct(string $appName, IRequest $request){
           parent::__construct($appName, $request);
       }
       /**

     *
     * @return DataResponse
     */
    public function index() {
        return new DataResponse([
            'test'
        ]);
    }

}
```
Uses of Controller Function Annotations:
```
/**
 *@PublicPage public interface
 * @NoCSRFRequired does not do csrf checking
 * @NoAdminRequired don't know what to guess
 * @return DataResponse
 */
```

1. Create example/lib/AppInfo/Application.php to have a clearer code structure

   <?php
   namespace OCA\Example\AppInfo;
   
   use OCP\AppFramework\App;
   use \OCP\IContainer;
   use OCA\Example\Controller\ExampleController;
   
   
   class Application extends App {
   
       public function __construct(array $urlParams=array()){
           
           parent::__construct('example', $urlParams);
           
       }
       
       public function register(){
           
           $container = $this->getContainer();
   
           /**

         */
        $container->registerService('Example', function(IContainer $c) {
            return new ExampleController(
                $c->query('AppName'),
                $c->query('Request')
            );
        });
        
    }
}
```

1. Create application load and execution files
   Create the file example/appinfo/app.php

   <?php
   
   $app = new \OCA\Example\AppInfo\Application();
   $app->register();

2. Create routing
   example/appinfo/routes.php

   <?php
   
   return [
       'routes' => [
           ['name' => 'example#index', 'url' => '/', 'verb' => 'GET']
       ]
   ];

3. Create view
   To be continued