如何处理dispatch_queue_t dispatch_get_local_queue dispatch_queue_create EXC BAD ACCESS？

Question

我有以下代码

dispatch_queue_t dispatch_get_local_queue()
{
    static dispatch_queue_t _queue;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _queue = dispatch_queue_create("com.github.blackraccoon", 0);
        dispatch_queue_set_specific(_queue, "com.github.blackraccoon", (void*) "com.github.blackraccoon", NULL);
    });
    return _queue;
}

在行dispatch_queue_set_specific接收到信号EXC BAD ACCESS之后。怎么处理这个？使用iphone 5.0模拟器，一切正常。但与iphone 4.3模拟器和ipad 4.2的ipad崩溃。它是BlackRaccoon项目的一部分。在我之后

createDir = [BRRequestCreateDirectory initWithDelegate: self];
createDir.path = [NSString stringWithFormat:@"/%@/",strProjectID];
createDir.hostname = @"cite";
createDir.username = @"username";
createDir.password = @"password";
[createDir start];