An instance 0x17003c6c0 of class AVKeyPathFlattener was deallocated while key value observers were still registered with it.

[Wakever]

楼主遇到过这个问题吗，我查了类AVKeyPathFlattener是在ios10之后的稀有类，而且这个崩溃是在子线程发生的，困扰了很久，知道的话帮忙解答一下，谢谢。