Add Image Size in Wordpress not working - php

Question

I'm trying to add images sizes on my wordpress site. I searched alot and tried too many solutions but couldn't work for me can anyone help me on this, it will be appreciatable. Thanks in advance. I have added this code in my functions.php file
add_filter( 'image_size_names_choose', 'my_custom_sizes' );
function my_custom_sizes( $sizes ) {
return array_merge( $sizes, array(
'slider_image_desktop' => __( 'slider_image_desktop' ),
) );
}
add_action( 'after_setup_theme', 'wpse_setup_theme' );
function wpse_setup_theme() {
add_theme_support( 'post-thumbnails' );
add_image_size( 'slider_image_desktop2', 60, 60, true );
}

Answer 1

Thanks everyone i solved my problem. I changed my some lines of code to
add_action( 'after_setup_theme', 'wpse_setup_theme' );
function wpse_setup_theme() {
add_theme_support( 'post-thumbnails' );
if ( function_exists( 'add_image_size' ) ) {
add_image_size( 'slider_image_desktop2', 60, 60, true );
}
}
It made the thumbnail then for retrieving i didn't use function for get image thumb because i am using Advanced Custom Fields so in wp admin in my acf fields group i just checked my image uploader's return value as image array and i just got full array of the uploaded image with my defined size. there was no need to use wp_get_attachment_image_src or wp_get_attachment_image function to fetch the image..
Thanks everyone for your help may this answer will help someone who will have been the same problem...

Answer 2

Try This:
$attachment_id = get_field('field_name');
$size = "slider_image_desktop2"; // (thumbnail, medium, large, full or custom size)
$image = wp_get_attachment_image_src( $attachment_id, $size );
// url = $image[0];
// width = $image[1];
// height = $image[2];
?>
<img class="image-class" alt="" src="<?php echo $image[0]; ?>" />
<?php

Answer 3

just copy and paste on your theme function.php file
add_image_size( 'img-cropped', 198, 198, true );// you can change the size

Answer 4

Your selected self answer was an absolute life saver, and got me to the point of what I was trying to do - but I had to make one small addition to get the custom image size in the backend page editor "add media" options:
function nmg_custom_sizes( $sizes ) {
return array_merge( $sizes, array(
'social-icons' => __('Social Icon'),
) );
}
add_action( 'after_setup_theme', 'nmg_setup_theme' );
function nmg_setup_theme() {
add_theme_support( 'post-thumbnails' );
if ( function_exists( 'add_image_size' ) ) {
add_image_size('social-icons', 9999, 60, false);
}
add_filter( 'image_size_names_choose', 'nmg_custom_sizes' );
}
It's your function, but with the function to add the custom size to image_size_names_choose - but after theme setup (what was stopping it from working for me before).
Might be useful to someone...