Ios8 如何在UICollectionViewController中缓存图像

我正在开发图片库应用程序。在集合视图中，我显示拇指。每次，我滚动集合视图，应用程序读取并再次打开图像。一段时间后，会出现内存警告。我想缓存图像。然后，当我滚动集合视图时，应用程序读取缓存的图像，而不是打开一个新图像

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    AllViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:IdAllCell forIndexPath:indexPath];

    NSArray *arrInfo = [self.arrThangkaInfo objectAtIndex:indexPath.row];

    // Cell Image
    NSString *thumbImageName = [self getValue:@"thumb_image" forRecord:arrInfo];
    NSString *imagePath = [NSString stringWithFormat:@"%@/%@", self.thumbFolder, thumbImageName];
    UIImage *originalImage = [UIImage imageWithContentsOfFile:imagePath];

    [cell.imageView setContentMode:UIViewContentModeScaleAspectFit];
    [cell.imageView setImage:originalImage];

    // Cell Label
    NSString *name = [self getValue:@"name" forRecord:arrInfo];

    [cell.nameLabel setTextAlignment:NSTextAlignmentCenter];
    [cell.nameLabel setTextColor:[UIColor blackColor]];
    [cell.nameLabel setBackgroundColor:[UIColor clearColor]];
    [cell.nameLabel setText:name];

    [cell setBackgroundColor:[UIColor clearColor]];

    return cell;
}