learndash_quiz_content

 <?php
/**
 * Example usage for learndash_quiz_content filter.
 */
add_filter(
	'learndash_quiz_content',
	function ( $quiz_content = '', WP_Post $quiz_post ) {

		// Set this logic to only effect certain Quizzes. Leave blank for all.
		$check_quiz_only = array( 107 );

		// Set our threshold limit. See https://codex.wordpress.org/Easier_Expression_of_Time_Constants for handy time constants
		$time_complete_threshold = 4 * HOUR_IN_SECONDS;

		if ( ( ! empty( $quiz_post ) ) && ( ( empty( $check_quiz_only ) ) || ( in_array( $quiz_post->ID, $check_quiz_only ) === true ) ) ) {
			$user_id           = get_current_user_id();
			$user_quiz_results = get_user_meta( $user_id, '_sfwd-quizzes', true );

			if ( ! empty( $user_quiz_results ) ) {
				// We reverse the user quizzes since newer items are added to the bottom.
				$user_quiz_results = array_reverse( $user_quiz_results );

				// Then we loop newest to oldest...
				foreach ( $user_quiz_results as $user_quiz_result ) {
					// ...until we find a match between the result quiz ID and the quiz post ID.
					if ( $user_quiz_result['quiz'] == $quiz_post->ID ) {
						// Check if the result quiz completed time is within out threshold.
						if ( ( $user_quiz_result['completed'] + $time_complete_threshold ) > time() ) {
							// If it is we display an alternate quiz content.
							$quiz_content = '<p>Too soon. Try again in about ' . human_time_diff( ( $user_quiz_result['completed'] + $time_complete_threshold ), time() ) . '.</p>';
						}
					}
				}
			}
		}

		// Always return $quiz_content;
		return $quiz_content;

	},
	10,
	2
);

add_filter(
	'learndash_quiz_content',
	function ( $quiz_content = '', WP_Post $quiz_post ) {
		$quiz_completed = learndash_is_quiz_complete( get_current_user_id(), $quiz_post->ID );
		if ( $quiz_completed ) {
			$quiz_content = '<p>You have already passed this Quiz.</p>';
		}

		// Always return $quiz_content;
		return $quiz_content;

	},
	10,
	2
);