UICollectionView布局更新 - 项目大小不变

Question

我遇到了collectionView项目大小的问题.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是如何改变的.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);
}