Create Custom Activity Group Feed in The Activity Stream

yzc_add_custom_group_activity_directory_tab.php

<?php
/**
 * Create Custom Activity Group Feed in The Activity Stream
 */
function yzc_add_custom_group_activity_directory_tab() {

    $tab_title = __( 'Custom Group', 'youzer' );

    ?>
    <li id="activity-custom-group">
        <a href="<?php echo esc_url( bp_loggedin_user_domain() . bp_get_activity_slug() . '/custom-group' ); ?>"><?php echo $tab_title; ?></a>
    </li>

    <?php
}

// Add Group Before All Members Tab0
add_action( 'bp_before_activity_type_tab_all', 'yzc_add_custom_group_activity_directory_tab' );

/**
 * Filter Activity By Group ID.
 */
function yzc_custom_group_filter_activity_scope( $retval = array(), $filter = array() ) {

    // Determine Custom Groups ID.
    $group_ids = array( 1 );

    // Determine the user_id.
    if ( ! empty( $filter['user_id'] ) ) {
        $user_id = $filter['user_id'];
    } else {
        $user_id = bp_displayed_user_id()
            ? bp_displayed_user_id()
            : bp_loggedin_user_id();
    }

    // Should we show all items regardless of sitewide visibility?
    $show_hidden = array();
    if ( ! empty( $user_id ) && ( $user_id !== bp_loggedin_user_id() ) ) {
        $show_hidden = array(
            'column' => 'hide_sitewide',
            'value'  => 0
        );
    }

    $retval = array(
        'relation' => 'AND',
        array(
            'relation' => 'AND',
            array(
                'column' => 'component',
                'value'  => buddypress()->groups->id
            ),
            array(
                'column'  => 'item_id',
                'compare' => 'IN',
                'value'   => (array) $group_ids
            ),
        ),
        $show_hidden,

        // Overrides.
        'override' => array(
            'filter'      => array( 'user_id' => 0 ),
            'show_hidden' => true
        ),
    );


    return $retval;
}

add_filter( 'bp_activity_set_custom-group_scope_args', 'yzc_custom_group_filter_activity_scope', 10, 2 );