set_url_scheme( string $url, string|null $scheme = null )

Sets the scheme for a URL.

Parameters

$url

(string) (Required) Absolute URL that includes a scheme

$scheme

(string|null) (Optional) Scheme to give $url. Currently 'http', 'https', 'login', 'login_post', 'admin', 'relative', 'rest', 'rpc', or null.

Default value: null

Return

(string) URL with chosen scheme.

Source

File: wp-includes/link-template.php 

function set_url_scheme( $url, $scheme = null ) {
	$orig_scheme = $scheme;

	if ( ! $scheme ) {
		$scheme = is_ssl() ? 'https' : 'http';
	} elseif ( 'admin' === $scheme || 'login' === $scheme || 'login_post' === $scheme || 'rpc' === $scheme ) {
		$scheme = is_ssl() || force_ssl_admin() ? 'https' : 'http';
	} elseif ( 'http' !== $scheme && 'https' !== $scheme && 'relative' !== $scheme ) {
		$scheme = is_ssl() ? 'https' : 'http';
	}

	$url = trim( $url );
	if ( substr( $url, 0, 2 ) === '//' ) {
		$url = 'http:' . $url;
	}

	if ( 'relative' === $scheme ) {
		$url = ltrim( preg_replace( '#^\w+://[^/]*#', '', $url ) );
		if ( '' !== $url && '/' === $url[0] ) {
			$url = '/' . ltrim( $url, "/ \t\n\r\0\x0B" );
		}
	} else {
		$url = preg_replace( '#^\w+://#', $scheme . '://', $url );
	}

	/**
	 * Filters the resulting URL after setting the scheme.
	 *
	 * @since 3.4.0
	 *
	 * @param string      $url         The complete URL including scheme and path.
	 * @param string      $scheme      Scheme applied to the URL. One of 'http', 'https', or 'relative'.
	 * @param string|null $orig_scheme Scheme requested for the URL. One of 'http', 'https', 'login',
	 *                                 'login_post', 'admin', 'relative', 'rest', 'rpc', or null.
	 */
	return apply_filters( 'set_url_scheme', $url, $scheme, $orig_scheme );
}

Uses

Uses Description
wp-includes/load.php: is_ssl()

Determines if SSL is used.
wp-includes/functions.php: force_ssl_admin()

Whether to force SSL used for the Administration Screens.
wp-includes/link-template.php: set_url_scheme

Filters the resulting URL after setting the scheme.
wp-includes/plugin.php: apply_filters()

Calls the callback functions that have been added to a filter hook.

Used By

Used By Description
wp-includes/rest-api/endpoints/class-wp-rest-pattern-directory-controller.php: WP_REST_Pattern_Directory_Controller::get_items()

Search and retrieve block patterns metadata
wp-includes/feed.php: get_self_link()

Returns the link for the currently displayed feed.
wp-admin/includes/misc.php: wp_check_php_version()

Checks if the user needs to update PHP.
wp-includes/class-wp-customize-manager.php: WP_Customize_Manager::handle_load_themes_request()

Load themes into the theme browsing/installation UI.
wp-admin/includes/class-wp-community-events.php: WP_Community_Events::get_events()

Gets data about events near a particular location.
wp-includes/theme.php: get_header_video_url()

Retrieves header video URL for custom header.
wp-includes/rest-api.php: get_rest_url()

Retrieves the URL to a REST endpoint on a site.
wp-includes/media.php: wp_calculate_image_srcset()

A helper function to calculate the image sources to include in a ‘srcset’ attribute.
wp-includes/link-template.php: get_preview_post_link()

Retrieves the URL used for the post preview.
wp-includes/link-template.php: get_avatar_data()

Retrieves default data about the avatar.
wp-admin/includes/misc.php: wp_admin_canonical_url()

Remove single-use URL parameters and create canonical link based on new URL.
wp-admin/includes/translation-install.php: translations_api()

Retrieve translations from WordPress Translation API.
wp-admin/includes/theme.php: themes_api()

Retrieves theme installer pages from the WordPress.org Themes API.
wp-admin/includes/class-wp-list-table.php: WP_List_Table::pagination()

Displays the pagination.
wp-admin/includes/class-wp-list-table.php: WP_List_Table::print_column_headers()

Prints column headers, accounting for hidden and sortable columns.
wp-admin/includes/update.php: get_core_checksums()

Gets and caches the checksums for the given version of WordPress.
wp-admin/includes/dashboard.php: wp_check_browser_version()

Checks if the user needs a browser update.
wp-admin/includes/plugin-install.php: plugins_api()

Retrieves plugin installer pages from the WordPress.org Plugins API.
wp-admin/includes/plugin.php: add_menu_page()

Add a top-level menu page.
wp-admin/includes/media.php: edit_form_image_editor()

Displays the image and editor in the post editor
wp-admin/includes/ajax-actions.php: wp_ajax_query_themes()

Ajax handler for getting themes from themes_api().
wp-admin/includes/file.php: get_home_path()

Gets the absolute filesystem path to the root of the WordPress installation.
wp-admin/includes/import.php: wp_get_popular_importers()

Returns a list from WordPress.org of popular importer plugins.
wp-admin/includes/credits.php: wp_credits()

Retrieve the contributor credits.
wp-admin/includes/class-custom-image-header.php: Custom_Image_Header::show_header_selector()

Display UI for selecting one of several default headers.
wp-admin/includes/class-custom-background.php: Custom_Background::admin_page()

Display the custom background page.
wp-includes/theme.php: _custom_background_cb()

Default custom background callback.
wp-includes/theme.php: get_header_image()

Retrieves header image for custom header.
wp-includes/pluggable.php: auth_redirect()

Checks if a user is logged in, if not it redirects them to the login page.
wp-includes/deprecated.php: url_is_accessable_via_ssl()

Determines if the URL can be accessed over SSL.
wp-includes/link-template.php: content_url()

Retrieves the URL to the content directory.
wp-includes/link-template.php: plugins_url()

Retrieves a URL within the plugins or mu-plugins directory.
wp-includes/link-template.php: network_site_url()

Retrieves the site URL for the current network.
wp-includes/link-template.php: network_home_url()

Retrieves the home URL for the current network.
wp-includes/link-template.php: get_home_url()

Retrieves the URL for a given site where the front end is accessible.
wp-includes/link-template.php: get_site_url()

Retrieves the URL for a given site where WordPress application files (e.g. wp-blog-header.php or the wp-admin/ folder) are accessible.
wp-includes/update.php: wp_version_check()

Check WordPress version against the newest version.
wp-includes/update.php: wp_update_plugins()

Checks for available updates to plugins based on the latest versions hosted on WordPress.org.
wp-includes/update.php: wp_update_themes()

Checks for available updates to themes based on the latest versions hosted on WordPress.org.
wp-includes/nav-menu-template.php: _wp_menu_item_classes_by_context()

Adds the class property classes for the current context, if applicable.
wp-includes/media.php: wp_video_shortcode()

Builds the Video shortcode output.
wp-includes/post.php: wp_get_attachment_url()

Retrieve the URL for an attachment.
wp-includes/rewrite.php: url_to_postid()

Examine a URL and try to determine the post ID it represents.
wp-includes/ms-functions.php: filter_SSL()

Formats a URL to use https.
wp-includes/ms-deprecated.php: install_blog()

Install an empty blog.
wp-includes/class-wp-xmlrpc-server.php: wp_xmlrpc_server::_multisite_getUsersBlogs()

Private function for retrieving a users blogs for multisite setups
wp-includes/class-wp-editor.php: _WP_Editors::editor_settings()

Changelog

Version Description
4.4.0 The 'rest' scheme was added.
3.4.0 Introduced.

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Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/functions/set_url_scheme