Fatal error: Class 'Slim\Slim' not found in C:\...\index.php on line 15

Ok, Slim/Views is also not compatible with Slim 3.0, so to get Slim 3.0 working with twig template files you need to do the following.

From composer:

require Slim/Slim
require Slim/twig-view

if you already added slim/views

remove Slim/Views

Then in the php, you need to use the following code snippets to make your twig files run

// Initalise use of templates

// Ensure debugging

$configuration = [
'settings' => [
    'displayErrorDetails' => true,
],
];

// Create container

$container = new \Slim\Container($configuration);

// Register component on container

$container['view'] = function ($c)
{
    $view = new \Slim\Views\Twig('templates', [
        'cache' => 'cache'
    ]);
    $view->addExtension(new \Slim\Views\TwigExtension
    (
        $c['router'],
        $c['request']->getUri()
    ));
    return $view;
};

// Create app

 $app = new \Slim\App($container);

// Render Twig template in route **

$app->get('/', function ($request, $response, $args)
{
    return $this->view->render($response, 'login.twig',
    [
        'name' => "Log In"
    ]);
})->setName('home');

// Run app

$app->run();

Notes for this code:

** in the documentation, this snippet was originally

$app->get('/hello/{name}', function ($request, $response, $args)
{
    return $this->view->render($response, 'profile.html', [
    'name' => $args['name']
]);
})->setName('profile');

I changed the code

$app->get('/hello/{name}', function ($request, $response, $args)

to

$app->get('/', function ($request, $response, $args)

as I wanted this to catch requests to my home page, and then I also changed

'name' => $args['name'] 

to

'name' => "Log In" 

As a quick way to kill an error message for the {name} component that I'm not using on my page. As I wasn't passing in any args I decided to just hard code this to a String value as a quick hack to make everything work smoothly :p.

Sources:

Main code: http://www.slimframework.com/docs/

Twig component: http://www.slimframework.com/docs/features/templates.html

Error handling: http://www.slimframework.com/docs/handlers/error.html

The point is about finding the file path of Slim.php within installed Slim folder.

Given version differences and where you choose to install composer, Slim.php might be located differently, so try to locate the file and include the file path in your code. For instance: http://postimg.org/image/bm7sbkfc5/

Very helpful Branden! Thank you!!

Thank you very much.