class-custom-post-template.php

<?php
if ( ! class_exists( 'Custom_Post_Template' ) ) {

	class Custom_Post_Template {

        const POST_TYPE = 'post'; // what ppst type would you like to make this template for
        
		public function __construct() {

			add_action( 'init', array( &$this, 'init' ) );
      add_filter( 'gettext', array( &$this, 'add_custom_post_placeholder' ) );
            
    } // END __construct
        
		public function init() {
    
			$this->custom_post_template();
      
		} // END init

		public function add_custom_post_placeholder( $input ) {
    
			global $post_type;
      
			if ( is_admin() && 'Add title' == $input && self::POST_TYPE == $post_type ) {
      
				return 'Enter A Post Title Here';
        
			}
			return $input;
      
    } // END add_custom_post_placeholder

		public function custom_post_template() {
    
			$custom_post_template = array(
                array(
                    'core/columns', // note outer is plural columnS
                    array('className'=>'container-classname'), // give the template column a class
                    array( 
                        array(
                            'core/column', // note singular inner column (no S)
                            array('className'=>'post-custom-col'), // give the template inner column a class
                            array( 
                                array(
                                    'core/paragraph', // set a paragraph block inside your custom column template
                                    array(
                                        'className'=>'custom-paragraph-class', // give the template inner column a class
                                        'placeholder' => 'Add content or additional blocks' // set placeholder text
                                    )
                                ),
                            )
                        ),
                        array(
                            'core/column', // note singular inner column (no S)
                            array('className'=>'post-custom-col-b'), // give the template inner column a class
                            array(
                                array(
                                    'core/list', // set a list block inside your custom column template
                                    array( 'placeholder' => 'write list' ) // set placeholder text
                                ),
                            )
                        ),
                    ) 
                ),
                array(
                    'core/paragraph',// set a paragraph block after your custom template columns
                    array(
                        'className'=>'custom-paragraph-class',// give the first default paragrapha class
                        'placeholder' => 'Add content or additional blocks' // set placeholder text
                    )
                ),
            );
            $post_type_object = get_post_type_object( self::POST_TYPE );
            $post_type_object->template = $custom_post_template;
            
		}
    
	} // END class Custom_Post_Template
  
} // END if class_exists

$custom_post_template = new Custom_Post_Template();