ios - NSFileSystemFreeSize : translating result into user friendly display of mb/gb?

Question

有没有人有将 NSFileSystemFreeSize 的结果转换为用户友好的可用 mb/gb 字符串的例程。我以为我已经掌握了它的要点，但我得到了奇怪的结果。

- (NSString*)getFreeSpace
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,     NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];

NSDictionary* fileAttributes = [[NSFileManager defaultManager] attributesOfFileSystemForPath:documentsDirectory error:NULL];
unsigned long long freeSpaceInBytes = [[fileAttributes objectForKey:NSFileSystemFreeSize] unsignedLongLongValue];

NSString * space = [NSString stringWithFormat:@"Free Space: %fll", freeSpaceInBytes /1024. / 1024. /1024.]; 

NSLog(@"freeSpaceInBytes %llull %fll", freeSpaceInBytes, freeSpaceInBytes /1024. / 1024. /1024.);

return space;
}

Answer 1

static NSString* prettyBytes(uint64_t numBytes)
{
    uint64_t const scale = 1024;
    char const * abbrevs[] = { "EB", "PB", "TB", "GB", "MB", "KB", "Bytes" };
    size_t numAbbrevs = sizeof(abbrevs) / sizeof(abbrevs[0]);
    uint64_t maximum = powl(scale, numAbbrevs-1);
    for (size_t i = 0; i < numAbbrevs-1; ++i) {
        if (numBytes > maximum) {
            return [NSString stringWithFormat:@"%.4f %s", numBytes / (double)maximum, abbrevs[i]];
        }
        maximum /= scale;
    }
    return [NSString stringWithFormat:@"%u Bytes", (unsigned)numBytes];
}