iOS开发之获得当前线程

闲话少说直接上代码

dispatch_queue_t queueA = dispatch_queue_create("com.effectiveobjective.queueA", NULL);
dispatch_queue_t queueB = dispatch_queue_create("com.effectiveobjective.queueB", NUL);
dispatch_set_target_queue(queueB, queueA);

static int kQueueSpecific;
CFStringRef queueSpecificValue = CFSTR("queueA");
dispatch_queue_set_specific(queueA, //
                                                 &kQueueSpecific, //key
                                                 (void *)queueSpecificValue, //value
                                                 (dispatch_function_t)CFRelease);

dispatch_sync(queueB, ^{
   dispatch_block_t block = ^{
      NSLog(@"No deadLock!");
   };
   CFStringRef retrieveValue = dispatch_get_specific(&kQueueSpecific);
    if(retrievedValue){
       block;
    }else{
       dispatch_queue(queueA, block);
    }
});