Question

我对collectionView的项目大小有疑问。我想在纵向模式中显示3个项目，在横向模式下显示6个项目。我已经设置了像这样的-layoutSubviews：

- (void)layoutSubviews {
    [super layoutSubviews];

    if ([[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationPortrait || ([[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationPortraitUpsideDown)) {
        //Portrait orientation
        self.flowLayoutPortrait.itemSize = CGSizeMake(106, 106);

    } else if ([[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationLandscapeLeft || ([[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationLandscapeRight)) {
        //Landscape orientation
        self.flowLayoutPortrait.itemSize = CGSizeMake(93, 93);
    }
    [self.collectionView.collectionViewLayout invalidateLayout];
}

但是单元格大小不会更新，它对于两个方向始终保持不变。如果我创建2个flowLayouts并使用：

[self.collectionView setCollectionViewLayout:self.flowLayoutLandscape];

一切正常，但我真的不喜欢它们的改变方式。动画真的很糟糕。而且因为itemSize是唯一需要更新的属性，所以使用1布局似乎是最佳选择。

如何告诉collectionView更新布局？

Answer 1

我使用这种方法，这对我来说非常好：

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
    if (_isLandscape)
        return CGSizeMake(yourLandscapeWidth, yourLandscapeHeight);
    else
        return CGSizeMake(yourNonLandscapeWidth, yourNonLandscapeHeight);
}

Answer 2

可能是您可以使用不同标识符的纵向/横向模式的不同单元格。比你只需要为集合视图重新加载数据而不是它肯定有效。

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    if ([[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationPortrait || ([[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationPortraitUpsideDown)) {
        //Portrait orientation
        //dequeue cell for portrait mode

    } else if ([[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationLandscapeLeft || ([[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationLandscapeRight)) {
        //Landscape orientation
        //dequeue cell for landscape mode
    }

    return cell;
}

UICollectionView布局更新 - 项目大小不变

2 个答案: