获取iOS文件夹大小（空间占用）

+ (float)calculateFileSizeInUnit:(unsigned long long)contentLength
{
    if(contentLength >= pow(1024, 3))
        return (float) (contentLength / (float)pow(1024, 3));
    else if(contentLength >= pow(1024, 2))
        return (float) (contentLength / (float)pow(1024, 2));
    else if(contentLength >= 1024)
        return (float) (contentLength / (float)1024);
    else
        return (float) (contentLength);
}
+ (NSString *)calculateUnit:(unsigned long long)contentLength
{
    if(contentLength >= pow(1024, 3))
        return @"GB";
    else if(contentLength >= pow(1024, 2))
        return @"MB";
    else if(contentLength >= 1024)
        return @"KB";
    else
        return @"Bytes";
}
+ (float ) folderSizeAtPath:(NSString*) folderPath{
    NSFileManager* manager = [NSFileManager defaultManager];
    if (![manager fileExistsAtPath:folderPath]) return 0;
    NSEnumerator *childFilesEnumerator = [[manager subpathsAtPath:folderPath] objectEnumerator];
    NSString* fileName;
    long long folderSize = 0;
    while ((fileName = [childFilesEnumerator nextObject]) != nil){
        NSString* fileAbsolutePath = [folderPath stringByAppendingPathComponent:fileName];
        folderSize += [self fileSizeAtPath:fileAbsolutePath];
    }
    return folderSize;
}
+ (long long) fileSizeAtPath:(NSString*) filePath{
    NSFileManager* manager = [NSFileManager defaultManager];
    if ([manager fileExistsAtPath:filePath]){
        return [[manager attributesOfItemAtPath:filePath error:nil] fileSize];
    }
    return 0;
}

+(NSString *)folderSizeStringAtPath:(NSString*) filePath
{
    float size=[self folderSizeAtPath:filePath];
    NSString *fileSizeString=[NSString stringWithFormat:@"%.02f%@",[self calculateFileSizeInUnit:size],[self calculateUnit:size]];
    return fileSizeString;
}