删除指定目录下所有文件 可以用于指定清空缓存

- (float ) folderSizeAtPath:(NSString*) folderPath{

    NSFileManager* manager = [NSFileManagerdefaultManager];

    if (![manager fileExistsAtPath:folderPath])return 0;

    NSEnumerator *childFilesEnumerator = [[managersubpathsAtPath:folderPath] objectEnumerator];

    NSString* fileName;

    long long folderSize =0;

    while ((fileName = [childFilesEnumeratornextObject]) != nil){

        NSString* fileAbsolutePath = [folderPathstringByAppendingPathComponent:fileName];

        folderSize += [self fileSizeAtPath:fileAbsolutePath];

    }

    return folderSize/(1024.0*1024.0);

}

- (long long) fileSizeAtPath:(NSString*) filePath{

    NSFileManager* manager = [NSFileManagerdefaultManager];

    if ([manager fileExistsAtPath:filePath]){

        return [[managerattributesOfItemAtPath:filePath error:nil]fileSize];

    }

    return 0;

}