调试时面临警告问题

Question

背景

我正在拍摄viewController的截图，并在collectionViewCell中展示。collectionViewCell的布局是水平的，但是当我选择一个视图，然后旋转设备，然后返回到collectionView，布局是垂直的。

要调试:我在代码中放置了一个断点，在调试区域，我试图检查变量的输出，这是下面的警告开始出现的地方。

**Warning:**

error: property 'modalPresentationStyle' declared with incompatible types in different translation units ('UIModalPresentationStyle' vs. 'UIModalPresentationStyle')
error: instance method 'modalPresentationStyle' has incompatible result types in different translation units ('UIModalPresentationStyle' vs. 'UIModalPresentationStyle')
error: property 'modalPresentationStyle' declared with incompatible types in different translation units ('UIModalPresentationStyle' vs. 'UIModalPresentationStyle')
error: instance method 'modalPresentationStyle' has incompatible result types in different translation units ('UIModalPresentationStyle' vs. 'UIModalPresentationStyle')
error: property 'modalPresentationStyle' declared with incompatible types in different translation units ('UIModalPresentationStyle' vs. 'UIModalPresentationStyle')
error: instance method 'modalPresentationStyle' has incompatible result types in different translation units ('UIModalPresentationStyle' vs. 'UIModalPresentationStyle')
note: declared here with type 'UIModalPresentationStyle'
note: instance method 'modalPresentationStyle' also declared here
note: declared here with type 'UIModalPresentationStyle'
note: declared here with type 'UIModalPresentationStyle'
note: instance method 'modalPresentationStyle' also declared here
note: declared here with type 'UIModalPresentationStyle'
note: declared here with type 'UIModalPresentationStyle'
note: instance method 'modalPresentationStyle' also declared here
note: declared here with type 'UIModalPresentationStyle'
error: 6 errors parsing expression

我用的 :-

• Xcode版本: 7.1
• iOS: 9.1

注释--我在Xcode 6.4上使用iOS8运行的相同的代码，并且运行时没有出现故障/警告。此外，我还能够在调试区域中找到变量的值。

详细资料:-

断点- -我把它放在下面的方法中

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {

    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];

    UIViewController *viewController = (UIViewController *)_tabControllers[(NSUInteger)indexPath.row];

    /* Trying to debug above viewController in debug area */
    /* Some code is here also but of no use */

    cell.contentView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

    return cell;

}

在调试区域启动的命令-

po viewController

预期结果-

viewController的值，其细节类似于通常的框架。

实际结果-

上述警告。

我想要调试的东西-

collectionView单元格的布局在iOS 9中是自动变化的(在旋转后一个在下)，而iOS 8中的其他布局(水平视图)是完美的。

提前谢谢。

Answer 1

备选解决方案

基于您更新的关于想要处理UICollectionView旋转的评论。是否尝试将以下方法添加到包含集合视图的UIViewController中？

- (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator
{
    [super viewWillTransitionToSize:size withTransitionCoordinator:coordinator];

    [coordinator animateAlongsideTransition:nil completion:^(id<UIViewControllerTransitionCoordinatorContext> context) {
        [self.collectionView performBatchUpdates:^{
            [self.collectionView setCollectionViewLayout:self.collectionView.collectionViewLayout animated:YES];
        } completion:nil];
    }];
}

或

在旋转视图方法中，可以在invalidateLayout上调用UICollectionView。

或

您可以尝试将UIImageView放入集合视图单元格并使用自动布局。然后将视图控制器的快照设置为UIImageView上的图像。

来自苹果的CollectionView项目示例

80+关于SO的其他问题 (可能提供一些见解)

警告

关于你所看到的警告。您所说的不重要的代码很可能是为UIModalPresentationStyle类型的属性分配无效值造成的(如果没有更重要的代码，就很难达到更高的精度)。此外，您所展示的代码在使用管道( autoresizingMask )时也有一个小问题。这些代码可以编码为[UIViewAutoresizingFlexibleWidth, UIViewAutoresizingFlexibleHeight]。