警告

[xiaolingling1126]

真机运行的时候，会出现警告。
Main Thread Checker: UI API called on a background thread: -[UIButton canBecomeFocused]
PID: 8939, TID: 3103013, Thread name: (none), Queue name: kKeyboardManagerRespondersKey, QoS: 0
Backtrace:
4 Platform_Mobile 0x0000000104597fac -[UIView(JKFirstResponder) jk_canBecameFirstResponder] + 40
5 Platform_Mobile 0x000000010459835c __53-[UIView(JKFirstResponder) jk_traverseResponderViews]_block_invoke + 96
6 CoreFoundation 0x0000000185ad9b08 + 216
7 Platform_Mobile 0x0000000104598238 -[UIView(JKFirstResponder) jk_traverseResponderViews] + 224
8 Platform_Mobile 0x000000010454cc90 __46-[JKKeyboardManager jk_traverseResponderViews]_block_invoke + 132
9 libdispatch.dylib 0x0000000108d0d49c _dispatch_call_block_and_release + 24
10 libdispatch.dylib 0x0000000108d0d45c _dispatch_client_callout + 16
11 libdispatch.dylib 0x0000000108d1a800 _dispatch_continuation_pop + 592
12 libdispatch.dylib 0x0000000108d1909c _dispatch_async_redirect_invoke + 628
13 libdispatch.dylib 0x0000000108d1eb54 _dispatch_root_queue_drain + 616
14 libdispatch.dylib 0x0000000108d1e880 _dispatch_worker_thread3 + 136
15 libsystem_pthread.dylib 0x000000018582b130 _pthread_wqthread + 1268
16 libsystem_pthread.dylib 0x000000018582ac30 start_wqthread + 4