IOS计算缓存大小

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];

// 调用上面计算文件大小的方法fileSizeAtPath

        folderSize += [self fileSizeAtPath:fileAbsolutePath];

    }

    return folderSize/(1024.0*1024.0);

}