If, however, the callback function can be invoked after the call returns, the managed caller must take steps to ensure that the delegate remains uncollected until the callback function finishes.

• 然而,如果可以在调用返回后调用回调函数,则托管调用方必须采取相应的措施来确保委托在回调函数完成其工作之前不会被回收。