Question

我只修改了flowLayout中的属性

-(NSArray *)layoutAttributesForElementsInRect:(CGRect)rect {
    NSMutableArray *array = [[super layoutAttributesForElementsInRect:rect] mutableCopy];

    for (int i = 0; i< array.count; i++) {
        UICollectionViewLayoutAttributes* attributes = array[i];
        if (!attributes.representedElementKind) {
            array[i] = [self layoutAttributesForItemAtIndexPath:attributes.indexPath];
        }
    }
    return array;
}

- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewLayoutAttributes *attributes = [super layoutAttributesForItemAtIndexPath:indexPath];
    CGFloat midX = self.collectionView.contentOffset.x + self.collectionView.width * 0.5;
    CGFloat distance = midX - attributes.center.x;
    CGFloat activeDistance = self.collectionView.width - lineSpacing - remainSpacing * 2;
    CGFloat normalizedDistance = distance / activeDistance;
    attributes.alpha = 1 - (1 - alphaFactor) * ABS(normalizedDistance);
    CGFloat zoom = 1 - (1 - scaleFactor) * ABS(normalizedDistance);
    attributes.transform3D = CATransform3DMakeScale(1.0, zoom, 1.0);
    attributes.zIndex = 1;
    return attributes;
}

这样的问题，控制台在第一次更改显示的单元格时注销：

UICollectionViewFlowLayout缓存了索引路径{length = 2，path = 0 - 1}的帧不匹配 - 缓存值：{{350,15.75}，{265,283.5}};预期值：{{350,0}，{265,315}}

这可能是因为流布局子类MyFlowLayout正在修改UICollectionViewFlowLayout返回的属性而不复制它们

Answer 1

这样做，复制属性

UICollectionViewLayoutAttributes *attributes = [[super layoutAttributesForItemAtIndexPath:indexPath] copy];

此问题在此问题中已解决： Warning: UICollectionViewFlowLayout has cached frame mismatch for index path 'abc'

警告使用自定义collectionViewFlowLayot

1 个答案: