iOS之解决崩溃Collection <__NSArrayM: 0xb550c30> was mutated while being enumerated.

崩溃提示：Terminating app due to uncaught exception 'NSGenericException', reason: '*** Collection <CALayerArray: 0x14df0bd0> was mutated while being enumerated.'崩溃提示：Terminating app due to uncaught except