ios – 根据UICollectionView中的图像动态更改单元格大小

-(void)setupCollectionView{
[self setupPageControlView];
self.screensCollectionView.delegate=self;
self.screensCollectionView.datasource=self;
[self.screensCollectionView registerNib:[UINib nibWithNibName:@"FGAppScreensCollectionViewItemCell" bundle:nil] forCellWithReusEIDentifier:@"screenCell"];


UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];
[flowLayout setScrollDirection:UICollectionViewScrollDirectionHorizontal];
[flowLayout setMinimumInteritemSpacing:0.0f];
[flowLayout setMinimumLinespacing:0.0f];
[flowLayout setItemSize:CGSizeMake(165,255)];
//[self.screensCollectionView setPagingEnabled:YES];
[self.screensCollectionView setCollectionViewLayout:flowLayout];

}

对于cellForRowATindexPath我下载这样的图像：

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemATindexPath:(NSIndexPath *)indexPath{
static NSString *cellIdentifier = @"screenCell";

FGAppScreensCollectionViewItemCell *cell = [collectionView dequeueReusableCellWithReusEIDentifier:cellIdentifier forIndexPath:indexPath];

NSURLrequest *urlrequest = [NSURLrequest requestWithURL:[NSURL URLWithString:[self.imageURLArray objectATindex:indexPath.row]]];

UIActivityInDicatorView *spinner = [[UIActivityInDicatorView alloc] initWithActivityInDicatorStyle:UIActivityInDicatorViewStyleGray];
[spinner startAnimaTing];
[spinner setFrame:CGRectMake(50,100,20,20)];
[cell.contentView addSubview:spinner];
[cell.screenImageView setImageWithURLrequest:urlrequest placeholderImage:nil success:^(NSURLrequest *request,NShttpURLResponse *response,UIImage *imagE) {
    //STOP THE SPINNER
    for (UIView* view in [cell.contentView subviews]) {
        if ([view isKindOfClass:[UIActivityInDicatorView class]]) {
            [view removeFromSuperview];
        }
    }
    cell.screenImageView.image = image;

} failure:^(NSURLrequest *request,NSError *error) {
    //
}];
[cell.screenImageView setImageWithURL:[NSURL URLWithString:[self.imageURLArray objectATindex:indexPath.row]]];
if (self.delegatE) {
      UITapGestureRecognizer* g = [[UITapGestureRecognizer alloc] initWithTarget:self.delegate action:@SELEctor(showPopUpImageView:)];
      [cell.screenImageView addGestureRecognizer:g];
}

return cell;

}

但是,集合视图中显示纵向和横向图像.肖像图像显示得很好,但在集合视图中景观图像看起来很小.我需要做的是根据图像大小调整单元格大小,以便填充正确的宽高比？

我添加了如下所示的方法,但问题是它在开始时一次调用所有单元格,并且一旦我在cellForRowATindexPath方法中下载图像就不会被调用：

- (CGSizE)collectionView:(UICollectionView *)collectionView
              layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemATindexPath:(NSIndexPath *)indexPath

{

return CGSizeMake(165,255);

}

因此,我想知道如何实现此功能,如果需要更多信息,请告诉我们？