Example PatrolExample.cs
Simple patrol behavior.
This will set the destination on the agent so that it moves through the sequence of objects in the targets array.
Version
Tested in the A* Pathfinding Project 4.1.0
using UnityEngine; 
using System.Collections;
using Pathfinding;
[HelpURL("https://arongranberg.com/astar/documentation/stable/class_patrol_example.php")]
public class PatrolExample : MonoBehaviour {
    public Transform[] targets;
    int index;
    IAstarAI agent;
    void Awake () {
        agent = GetComponent<IAstarAI>();
    }
    void Update () {
        if (targets.Length == 0) return;
        bool search = false;
        // Check if the agent has reached the current target.
        // We must check for 'pathPending' because otherwise we might
        // detect that the agent has reached the *previous* target
        // because the new path has not been calculated yet.
        if (agent.reachedEndOfPath && !agent.pathPending) {
            index = index + 1;
            search = true;
        }
        // Wrap around to the start of the targets array if we have reached the end of it
        index = index % targets.Length;
        agent.destination = targets[index].position;
        // Immediately calculate a path to the target.
        // Note that this needs to be done after setting the destination.
        if (search) agent.SearchPath();
    }
}