要导入 QML 类型到应用程序中，使用以下 import 语句在 .qml 文件中：
import QtScxml 5.15
更多信息，见 实例化状态机 .
| Connects to events sent out by state machines | |
| Provices access to the services invoked by state machines | |
| Provides an interface to the state machines created from SCXML files | |
| Dynamically loads an SCXML document and instantiates the state machine |
