M_PI'S π

Results 2 comments of M_PI'S π

临时解决方案是: ``` [JJException configExceptionCategory:JJExceptionGuardUnrecognizedSelector | JJExceptionGuardDictionaryContainer | JJExceptionGuardArrayContainer | JJExceptionGuardNSTimer | JJExceptionGuardNSNotificationCenter | JJExceptionGuardNSStringContainer]; ``` iOS11之后不手动移除Observer也没有问题.

## 更新 产生原因: iOS18竞态环境下产生dead lock. 解决方案: 异步执行 ``` dispatch_semaphore_wait(...) ... dispatch_semaphore_signal(..) ```