在obj-c app中崩溃的FSEventStreamCreate

Question

我试图对目录进行文件监控，从苹果文档中获取代码。它崩溃在fseventstreamcreate函数调用时出现此错误：

异常类型：EXC_BAD_ACCESS（SIGSEGV）
例外代码：KERN_INVALID_ADDRESS位于0x0000000000000008

我对目标C相当新（虽然我知道这是C代码，它是一个obj-c应用程序的一部分）并且真的不知道为什么会崩溃，这是一个noob错误。我很感激任何帮助。

void monitorCallback(
                 ConstFSEventStreamRef streamRef,
                 void *clientCallBackInfo,
                 size_t numEvents,
                 void *eventPaths,
                 const FSEventStreamEventFlags eventFlags[],
                 const FSEventStreamEventId eventIds[])
{
    int i;
    char **paths = (char**)eventPaths;

    // printf("Callback called\n");
    for (i=0; i<numEvents; i++) 
    {
        /* flags are unsigned long, IDs are uint64_t */
        printf("Change %llu in %s, flags %u\n", eventIds[i], paths[i], eventFlags[i]);
    }
}


- (void) monitorFolder
{
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    NSString * monitorFolder = [[NSUserDefaults standardUserDefaults] objectForKey:@"monitorFolder"];

    //Create stream to monitor for changes.
    CFArrayRef pathsToWatch = CFArrayCreate(NULL, (const void **)&monitorFolder, 1, NULL);
    FSEventStreamRef stream;
    CFAbsoluteTime latency = 3.0; /* Latency in seconds */

    /* Create the stream, passing in a callback */
    stream = FSEventStreamCreate(
        NULL,
        (FSEventStreamCallback)&monitorCallback,
        NULL,
        pathsToWatch,
        kFSEventStreamEventIdSinceNow,
        latency,
        kFSEventStreamCreateFlagNone );
    ...
}