NSFileManager包含非常丰富的信息，通过下面的方法可很容易的获取系统磁盘的大小和可用磁盘的大小

- (NSNumber *) totalDiskSpace
{
    NSDictionary *fattributes = [[NSFileManager defaultManager] fileSystemAttributesAtPath:NSHomeDirectory()];
    return [fattributes objectForKey:NSFileSystemSize];
}

- (NSNumber *) freeDiskSpace
{
    NSDictionary *fattributes = [[NSFileManager defaultManager] fileSystemAttributesAtPath:NSHomeDirectory()];
    return [fattributes objectForKey:NSFileSystemFreeSize];
}

参见NSFileManager的头文件尾部定义的字段，不难发现还有许多可以获取的信息的。

具体的都可以根据需求来获取。

FOUNDATION_EXPORT NSString * const NSFileType;
FOUNDATION_EXPORT NSString     * const NSFileTypeDirectory;
FOUNDATION_EXPORT NSString     * const NSFileTypeRegular;
FOUNDATION_EXPORT NSString     * const NSFileTypeSymbolicLink;
FOUNDATION_EXPORT NSString     * const NSFileTypeSocket;
FOUNDATION_EXPORT NSString     * const NSFileTypeCharacterSpecial;
FOUNDATION_EXPORT NSString     * const NSFileTypeBlockSpecial;
FOUNDATION_EXPORT NSString     * const NSFileTypeUnknown;
FOUNDATION_EXPORT NSString * const NSFileSize;
FOUNDATION_EXPORT NSString * const NSFileModificationDate;
FOUNDATION_EXPORT NSString * const NSFileReferenceCount;
FOUNDATION_EXPORT NSString * const NSFileDeviceIdentifier;
FOUNDATION_EXPORT NSString * const NSFileOwnerAccountName;
FOUNDATION_EXPORT NSString * const NSFileGroupOwnerAccountName;
FOUNDATION_EXPORT NSString * const NSFilePosixPermissions;
FOUNDATION_EXPORT NSString * const NSFileSystemNumber;
FOUNDATION_EXPORT NSString * const NSFileSystemFileNumber;
FOUNDATION_EXPORT NSString * const NSFileExtensionHidden;
FOUNDATION_EXPORT NSString * const NSFileHFSCreatorCode;
FOUNDATION_EXPORT NSString * const NSFileHFSTypeCode;
#if MAC_OS_X_VERSION_10_2 <= MAC_OS_X_VERSION_MAX_ALLOWED || __IPHONE_2_0 <= __IPHONE_OS_VERSION_MAX_ALLOWED
FOUNDATION_EXPORT NSString * const NSFileImmutable;
FOUNDATION_EXPORT NSString * const NSFileAppendOnly;
FOUNDATION_EXPORT NSString * const NSFileCreationDate;
FOUNDATION_EXPORT NSString * const NSFileOwnerAccountID;
FOUNDATION_EXPORT NSString * const NSFileGroupOwnerAccountID;
#endif
#if MAC_OS_X_VERSION_10_4 <= MAC_OS_X_VERSION_MAX_ALLOWED || __IPHONE_2_0 <= __IPHONE_OS_VERSION_MAX_ALLOWED
FOUNDATION_EXPORT NSString * const NSFileBusy;
#endif
#if __IPHONE_4_0 <= __IPHONE_OS_VERSION_MAX_ALLOWED
FOUNDATION_EXPORT NSString * const NSFileProtectionKey NS_AVAILABLE(NA, 4_0);
FOUNDATION_EXPORT NSString     * const NSFileProtectionNone NS_AVAILABLE(NA, 4_0);
FOUNDATION_EXPORT NSString     * const NSFileProtectionComplete NS_AVAILABLE(NA, 4_0);
#endif

FOUNDATION_EXPORT NSString * const NSFileSystemSize;
FOUNDATION_EXPORT NSString * const NSFileSystemFreeSize;
FOUNDATION_EXPORT NSString * const NSFileSystemNodes;
FOUNDATION_EXPORT NSString * const NSFileSystemFreeNodes;

@interface NSDictionary (NSFileAttributes)

- (unsigned long long)fileSize;
- (NSDate *)fileModificationDate;
- (NSString *)fileType;
- (NSUInteger)filePosixPermissions;
- (NSString *)fileOwnerAccountName;
- (NSString *)fileGroupOwnerAccountName;
- (NSInteger)fileSystemNumber;
- (NSUInteger)fileSystemFileNumber;
- (BOOL)fileExtensionHidden;
- (OSType)fileHFSCreatorCode;
- (OSType)fileHFSTypeCode;
#if MAC_OS_X_VERSION_10_2 <= MAC_OS_X_VERSION_MAX_ALLOWED || __IPHONE_2_0 <= __IPHONE_OS_VERSION_MAX_ALLOWED
- (BOOL)fileIsImmutable;
- (BOOL)fileIsAppendOnly;
- (NSDate *)fileCreationDate;
- (NSNumber *)fileOwnerAccountID;
- (NSNumber *)fileGroupOwnerAccountID;
#endif
@end