非 Task 对象，比如 MonoBehavior 组件，通过变量名获取变量的引用：

    1. behaviorTree.GetVariable("MyVariable");
    2. behaviorTree.SetVariable("MyVariable", value);
    3. behaviorTree.SetVariableValue("MyVariableName", value);

    真实例子：

    1. using UnityEngine;
    2. using BehaviorDesigner.Runtime;
    4. public class AccessVariable : MonoBehaviour
    5. {
    6.    public BehaviorTree behaviorTree;
    8.    public void Start()
    9.    {
    10.       var myIntVariable = (SharedInt)behaviorTree.GetVariable("MyVariable");
    11.       myIntVariable.Value = 42;
    12.    }
    13. }

    也可以获取全局变量：

    1. GlobalVariables.Instance.GetVariable("MyVariable");
    2. GlobalVariables.Instance.SetVariable("MyVariable", value);