获取 iPhone 剩余磁盘空间的代码

这段代码示范怎么取得 iPhone 的剩余磁盘空间，还有全部磁盘空间#include <sys/param.h>     #include <sys/mount.h>   long long freeSpace() {          struct statfs buf;          long long freespace = -1;          if(statfs("/", &buf) >= 0){              freespace = (long long)buf.f_bsize * buf.f_bfree;          }               return freespace;     }         +(float)getTotalDiskSpaceInBytes {            NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);            struct statfs tStats;            statfs([[paths lastObject] cString], &tStats);            float totalSpace = (float)(tStats.f_blocks * tStats.f_bsize);                   return totalSpace;       }