-[NSNull count]: unrecognized selector sent to instance 0x7fff8062db10
dynamic_cast error 2: One or more of the following type_info's has hidden visibility or is defined in more than one translation unit. They should all have public visibility. N10__cxxabiv116__shim_type_infoE, id, N10__cxxabiv117__pbase_type_infoE。
libc++abi.dylib: terminate_handler unexpectedly threw an exception
看代码NSNull count 是哪里调用了数组或者其他的 count获取数量，而该对象为null 导致crash
打开全局断点调试定位
