ios - Implicit declaration of function 'pthread_mutex

i trying lock method mutec article here states create member variable of class such

pthread_mutex_t mutex;

then initialize such

 pthread_mutex_init(&mutex, null);

then use such

void mylockingfunction() {     pthread_mutex_lock(&mutex);     // work.     pthread_mutex_unlock(&mutex); }

i getting following warning @ step 2 when initialize it.

implicit declaration of function 'pthread_mutex_init' invalid in c99

what mean ? should ignore ?

it means have not included header file declares function, compiler doesn't know @ point use it. you're trying implicitly declare using it, invalid.

if check man page pthread_mutex_init(), tells you should use following line import declaration:

#include <pthread.h>

if put near top of source file, warning go away.

UV code