调用startLoad方法会出现此bug

[Henry519]

Trapped uncaught exception 'NSGenericException', reason: '*** Collection <__NSArrayM: 0x60000044a860> was mutated while being enumerated.' [ 0 CoreFoundation 0x000000010df5ed4b __exceptionPreprocess + 171, 1 libobjc.A.dylib 0x0000000112cde21e objc_exception_throw + 48, 2 CoreFoundation 0x000000010dfc7f6c __NSFastEnumerationMutationHandler + 124, 3 WLMaster 0x000000010c46f6f5 -[ZFDownloadManager startLoad] + 1493, 4 WLMaster 0x000000010c46c895 -[ZFDownloadManager downFileUrl:filename:videoId:completeBlock:] + 2229, 5 WLMaster 0x000000010c563acd -[WLVideoCacheManager downloadWithData:completeBlock:] + 1325, 6 WLMaster 0x000000010c562fa5 __63-[WLVideoCacheManager addDownTaskToDispatchSemaphoreWithModle:]_block_invoke + 261, 7 libdispatch.dylib 0x000000011437f978 _dispatch_call_block_and_release + 12, 8 libdispatch.dylib 0x00000001143a90cd _dispatch_client_callout + 8, 9 libdispatch.dylib 0x0000000114388312 _dispatch_queue_override_invoke + 1426, 10 libdispatch.dylib 0x000000011438a385 _dispatch_root_queue_drain + 720, 11 libdispatch.dylib 0x000000011438a059 _dispatch_worker_thread3 + 123, 12 libsystem_pthread.dylib 0x0000000114758712 _pthread_wqthread + 1299, 13 libsystem_pthread.dylib 0x00000001147581ed start_wqthread + 13 ]

[ghost]

自己改改了，for循环改改