Upgrade Views
Documentations
What has been changed
- Your views look much like before, but they are invoked differently … instead of CI3’s - $this->load->view('x');, you can use- return view('x');.
- CI4 supports View Cells to build your response in pieces, and View Layouts for page layout. 
- The Template Parser is still there, and substantially enhanced. 
Upgrade Guide
- First, move all views to the folder app/Views 
- Change the loading syntax of views in every script where you load views:
- from - $this->load->view('directory_name/file_name')to- return view('directory_name/file_name');
- from - $content = $this->load->view('file', $data, TRUE);to- $content = view('file', $data);
 
 
- (optional) You can change the echo syntax in views from - <?php echo $title; ?>to- <?= $title ?>
- Remove the line - defined('BASEPATH') OR exit('No direct script access allowed');if it exists.
Code Example
CodeIgniter Version 3.x
Path: application/views:
<html>
<head>
    <title><?php echo html_escape($title); ?></title>
</head>
<body>
    <h1><?php echo html_escape($heading); ?></h1>
    <h3>My Todo List</h3>
    <ul>
    <?php foreach ($todo_list as $item): ?>
        <li><?php echo html_escape($item); ?></li>
    <?php endforeach; ?>
    </ul>
</body>
</html>
CodeIgniter Version 4.x
Path: app/Views:
<html>
<head>
    <title><?= esc($title) ?></title>
</head>
<body>
    <h1><?= esc($heading) ?></h1>
    <h3>My Todo List</h3>
    <ul>
    <?php foreach ($todo_list as $item): ?>
        <li><?= esc($item) ?></li>
    <?php endforeach ?>
    </ul>
</body>
</html>