取得当前硬盘空间

- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view.            NSFileManager *fm = [NSFileManager defaultManager];    NSDictionary *fattributes = [fm attributesOfFileSystemForPath:NSHomeDirectory() error:nil];            NSLog(@"容量%lldG",[[fattributes objectForKey:NSFileSystemSize] longLongValue]/1000000000);    NSLog(@"可用%lldG",[[fattributes objectForKey:NSFileSystemFreeSize] longLongValue]/1000000000);}