UICollectionViewCell 比 UICollectionview 高 y

Question

我的应用中有一个UICollectionView，我使用以下代码对其进行初始化：

UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
layout.itemSize = CGSizeMake(self.view.frame.size.width, self.view.frame.size.height);
[layout setScrollDirection:UICollectionViewScrollDirectionHorizontal];
self.collectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)
                                                     collectionViewLayout:layout];
self.collectionView.backgroundColor = [UIColor clearColor];
self.collectionView.delegate = self;
self.collectionView.dataSource = self;
[self.collectionView setPagingEnabled:YES];
[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"normalCell"];
[self.collectionView setShowsHorizontalScrollIndicator:NO];
[self.collectionView setShowsVerticalScrollIndicator:NO];
[self.view addSubview:self.collectionView];

然后我添加了所有的协议方法：

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
    return CGSizeMake(self.collectionView.frame.size.width, self.collectionView.frame.size.height);
}

- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section {
    return 0;
}

- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionView *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section {
    return 0;
}

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
    return 3;
}


- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    return 3;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"normalCell" forIndexPath:indexPath];

    if (indexPath.row == 0) {
        cell.backgroundColor = [UIColor blueColor];
    } else if (indexPath.row == 1) {
        cell.backgroundColor = [UIColor greenColor];
    } else if (indexPath.row == 2) {
        cell.backgroundColor = [UIColor yellowColor];
    }

    return cell;
}

- (void)viewDidLayoutSubviews {
    [super viewDidLayoutSubviews];
    UIEdgeInsets safeInsets = self.tabBarController.view.safeAreaInsets;

    NSLog(@"Top: %f", safeInsets.top);

    self.collectionView.frame = CGRectMake(0, safeInsets.top, self.view.frame.size.width, self.view.frame.size.height-safeInsets.top);
    [self.collectionView reloadData];
}

现在，UICollectionView 完美地放在了我的视野中。然而，UICollectionViewCell 的起点远高于 UICollectionView。

在下面的屏幕截图中，您可以看到该行为。蓝色为UICollectionViewCell，黄色为UICollectionView。如您所见，它的 y 坐标似乎比 UICollectionView 更高。

我已经绞尽脑汁好几个小时了，但我似乎无法弄清楚为什么会这样。有什么想法吗？

Answer 1

这里你根据 tabbarcontroller 设置单元格高度，所以它高于单元格高度只需设置单元格高度。