+ (long long)fileSizeAtPath:(NSString*)filePath
{
    NSFileManager* manager = [NSFileManager defaultManager];
    if ([manager fileExistsAtPath:filePath])
    {
        return [[manager attributesOfItemAtPath:filePath error:nil] fileSize];
    }
    return 0;
}

#pragma mark 計算目錄大小
+ (float)getCacheSizeFromFolder:(NSString *)folderName
{
    // 獲取Caches目錄路徑
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask,YES);

    NSString *folderPath;
    if (folderName == nil) {
        folderPath = [paths objectAtIndex:0];
    } else {
        NSString *cachePath = [paths objectAtIndex:0];
        folderPath = [cachePath stringByAppendingPathComponent:folderName];
    }

    NSFileManager* manager = [NSFileManager defaultManager];
    if (![manager fileExistsAtPath:folderPath]) return 0;
    NSEnumerator *childFilesEnumerator = [[manager subpathsAtPath:folderPath] objectEnumerator];//從前向后枚舉器
    NSString* fileName;
    long long folderSize = 0;
    while ((fileName = [childFilesEnumerator nextObject]) != nil)
    {
        NSLog(@"fileName ==== %@",fileName);
        NSString* fileAbsolutePath = [folderPath stringByAppendingPathComponent:fileName];
        NSLog(@"fileAbsolutePath ==== %@",fileAbsolutePath);
        folderSize += [self fileSizeAtPath:fileAbsolutePath];
    }
    NSLog(@"folderSize ==== %lld",folderSize);
    return folderSize/(1024.0*1024.0);
}
#pragma mark 清理緩存
+ (void)clearCacheFromFolder:(NSString *)folderName
{

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask,YES);

    NSString *path;
    if (folderName == nil) {
        path = [paths objectAtIndex:0];
    } else {
        NSString *cachePath = [paths objectAtIndex:0];
        path = [cachePath stringByAppendingPathComponent:folderName];
    }

    NSFileManager *fileManager=[NSFileManager defaultManager];
    if ([fileManager fileExistsAtPath:path]) {
        NSArray *childerFiles=[fileManager subpathsAtPath:path];
        for (NSString *fileName in childerFiles) {
            //如有需要，加入條件，過濾掉不想刪除的文件
            NSString *absolutePath=[path stringByAppendingPathComponent:fileName];
            [fileManager removeItemAtPath:absolutePath error:nil];
        }
    }
}