通常用于删除缓存的时，计算缓存大小

//单个文件的大小

-
 (long

long)
 fileSizeAtPath:(NSString*) filePath{

    NSFileManager*
 manager = [NSFileManager defaultManager];

    if

([manager fileExistsAtPath:filePath]){

        return

[[manager attributesOfItemAtPath:filePath error:nil] fileSize];

    }

    return

0;

}

//遍历文件夹获得文件夹大小，返回多少M

-
 (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/(1024.0*1024.0);

}