ios 带有 ContentInset 的 UICollectionView 不会一直向下滚动
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UICollectionView with ContentInset is not Scrolling all the Way Down
提问by electronix384128
I am setting the content inset of a UICollectionView:
我正在设置 UICollectionView 的内容插入：
[_collectionView setContentInset:UIEdgeInsetsMake(0.f, 0.f, 100.f, 0.f)];
Then I am scrolling programmatically all the way to the bottom of the UICollectionView with this method:
然后我用这个方法以编程方式滚动到 UICollectionView 的底部：
- (void)scrollToLastMessageAnimated:(BOOL)animated;
{
if (_messages.count == 0) { return; }
NSUInteger indexOfLastSection = _messagesBySections.count - 1;
NSInteger indexOfMessageInLastSection = [_messagesBySections[indexOfLastSection] count] - 1;
NSIndexPath *path = [NSIndexPath indexPathForItem:indexOfMessageInLastSection
inSection:indexOfLastSection];
[_collectionView scrollToItemAtIndexPath:path
atScrollPosition:UICollectionViewScrollPositionCenteredVertically
animated:animated];
}
It is scrolling down, but it is ignoring the contentInset, meaning that the last cells are below the specified content inset:
它向下滚动，但忽略了 contentInset，这意味着最后一个单元格低于指定的内容插入：
The left image, shows how it appear now after the view did appear. In the right image, I manually scrolled further down to the last message.
左图显示了视图出现后它现在的样子。在右图中，我手动向下滚动到最后一条消息。
I am using AutoLayout, any ideas why this happens?
我正在使用 AutoLayout，任何想法为什么会发生这种情况？
EDIT:
编辑：
Here is a screenshot of the IB setup:
这是IB设置的屏幕截图：
回答by electronix384128
Today, by chance I discovered the solution!
今天，我偶然发现了解决方案！
Select your view controller and uncheck the option "Adjust Scroll View Insets".
选择您的视图控制器并取消选中“调整滚动视图插入”选项。
With this option unchecked, iOS does not automatically adjust your insets of the view (and probably its subviews), which caused the problems for me ... Uncheck it and configure your scroll insets like this programmatically:
取消选中此选项后，iOS 不会自动调整您的视图插入（可能还有它的子视图），这给我带来了问题......取消选中它并以编程方式配置您的滚动插入：
- (void)configureInsetsOfCollectionView
{
[_collectionView setContentInset: UIEdgeInsetsMake(self.navigationController.navigationBar.bounds.size.height + [UIApplication sharedApplication].statusBarFrame.size.height + DEFAULT_SPACING, 0.f, _keyboardHeight + _toolbar.bounds.size.height + DEFAULT_SPACING, 0.f)];
[_collectionView setScrollIndicatorInsets:UIEdgeInsetsMake(self.navigationController.navigationBar.bounds.size.height + [UIApplication sharedApplication].statusBarFrame.size.height, 0.f, _keyboardHeight + _toolbar.bounds.size.height, 0.f)];
}
回答by Arjuna
If you are using flow layout try to set _collectionView.collectionViewLayout.sectionInset.
如果您使用流布局，请尝试设置 _collectionView.collectionViewLayout.sectionInset。
回答by Yoni Katz
swift version
快速版
collectionview.contentInset = UIEdgeInsetsMake(44,0,0,0)
collectionview.scrollIndicatorInsets = UIEdgeInsetsMake(44,0,0,0)
回答by E-Riddie
Possible Issue
可能的问题
You have set the collectionView below the toolbar and added constraints to bottom of superview for both views.
您已在工具栏下方设置了 collectionView 并为两个视图的超级视图底部添加了约束。
Solution
解决方案
Set the constraints of the toolbar to bottom, leading and set the width and height to fixed size. For your collectionView set the constraints to top, to bottom with the toolbar, leading to the superview and (alternative) with fixed size of width
将工具栏的约束设置为底部、前导并将宽度和高度设置为固定大小。对于您的 collectionView，使用工具栏将约束设置为顶部，底部，导致超级视图和（替代）具有固定大小的宽度
Update
更新
CollectionView
集合视图
Follow these steps to make it work:
请按照以下步骤使其工作：
Check your collection view, and don't put it below toolbar, and add these constraints by selecting your collectionView on Document Outline, click ctrl and drag it to your view, a popup will appear, hold shift and select these constraints.
检查您的集合视图，不要将其放在工具栏下方，并通过在文档大纲上选择您的集合视图来添加这些约束，单击 ctrl 并将其拖到您的视图中，将出现一个弹出窗口，按住 shift 并选择这些约束。
Toolbar
工具栏
Check the leading and bottom, by dragging with ctrl in view. And add fixed width and height for toolbar.
通过在视图中使用 ctrl 拖动来检查前导和底部。并为工具栏添加固定宽度和高度。
Dealing with scrolling before viewAppears
在 viewAppears 之前处理滚动
-(void)viewWillAppear:(BOOL)animated
{
[collectionView reloadData];
[self scrollToLastMessageAnimated:YES];
}
回答by T. Christiansen
You can set the referenceSizeForFooterInSectionfunction in your viewController class:
您可以referenceSizeForFooterInSection在 viewController 类中设置函数：
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
return CGSize(width: view.frame.width, height: 50)
}
Just set the height to your required value.
只需将高度设置为您需要的值。
