AVFoundation录制没有足够的磁盘空间错误代码11807

Question

我正在写一个只有100kb大小的视频。我的手机在磁盘上剩下大约20mb，但是当我尝试使用AVFoundation和AVCaptureMovieFileOutput创建录制时，我收到错误：

2014-06-15 10:40:19.511 wave[551:690b] ERROR: 
Error Domain=AVFoundationErrorDomain
Code=-11807 "Operation Stopped" UserInfo=0x157cde20 
{NSLocalizedRecoverySuggestion=There
is not enough available space to continue the file writing. 
Make room by deleting existing videos or photos

我正在设置

self.movieFileOutput.minFreeDiskSpaceLimit = //space available in bytes

认为它会覆盖这种默认行为，但事实并非如此。知道如何在给定磁盘空间参数的情况下继续允许记录吗？

更新 - 这是我用来获得可用空间的代码：

-(uint64_t)getFreeDiskspace {
    uint64_t totalSpace = 0;
    uint64_t totalFreeSpace = 0;
    NSError *error = nil;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSDictionary *dictionary = [[NSFileManager defaultManager] attributesOfFileSystemForPath:[paths lastObject] error: &error];

    if (dictionary) {
        NSNumber *fileSystemSizeInBytes = [dictionary objectForKey: NSFileSystemSize];
        NSNumber *freeFileSystemSizeInBytes = [dictionary objectForKey:NSFileSystemFreeSize];
        totalSpace = [fileSystemSizeInBytes unsignedLongLongValue];
        totalFreeSpace = [freeFileSystemSizeInBytes unsignedLongLongValue];
        NSLog(@"Memory Capacity of %llu MiB with %llu MiB Free memory available.", ((totalSpace/1024ll)/1024ll), ((totalFreeSpace/1024ll)/1024ll));
    } else {
        NSLog(@"Error Obtaining System Memory Info: Domain = %@", error);
    }

    return totalFreeSpace;
}