how let users select categories for posts in frontend?

Question

i've added a custom taxonomy to categorized post in colors other than their main category and i want to let users to categorized posts in frontend and i have no idea how to do that... is there anyway create a form to do this?

    function color() {

    $labels = array(
        'name'                       => 'Colors',
        'singular_name'              => 'Color',
        'menu_name'                  => 'Color',
        'all_items'                  => 'All Items',
        'parent_item'                => 'Parent Item',
        'parent_item_colon'          => 'Parent Item:',
        'new_item_name'              => 'New Item Name',
        'add_new_item'               => 'Add New Item',
        'edit_item'                  => 'Edit Item',
        'update_item'                => 'Update Item',
        'view_item'                  => 'View Item',
        'separate_items_with_commas' => 'Separate items with commas',
        'add_or_remove_items'        => 'Add or remove items',
        'choose_from_most_used'      => 'Choose from the most used',
        'popular_items'              => 'Popular Items',
        'search_items'               => 'Search Items',
        'not_found'                  => 'Not Found',
        'no_terms'                   => 'No items',
        'items_list'                 => 'Items list',
        'items_list_navigation'      => 'Items list navigation',
    );
    $args = array(
        'labels'                     => $labels,
        'hierarchical'               => true,
        'public'                     => true,
        'show_ui'                    => true,
        'show_admin_column'          => true,
        'show_in_nav_menus'          => true,
        'show_tagcloud'              => true,
    );
    register_taxonomy( 'color', array( 'post' ), $args );

}
add_action( 'init', 'color', 0 );

Answer 1

here is how to do it:

    <form action="#" method="post">
        <input type="checkbox" name="checklist[]" value="1"><label>Blue</label>
        <input type="checkbox" name="checklist[]" value="2"><label>Red</label>
...
        <input type="submit" name="submit" value="submit"/>
    </form>
    <?php
        if(isset($_POST['submit'])){
            if(!empty($_POST['checklist'])){
                $selectArr = array();
                foreach($_POST['checklist'] as $selected){
                    $selectedInt = (int)$selected;
                    $selectArr[] = $selectedInt;
                    wp_set_object_terms( $thePostId, $selectArr, 'color');
                }
            }
        }
    ?>

where the values in input tags are taxonomies IDs (color IDs)

and I used my theme functions to define current Post ID ($thePostId)