缩小UIScrollView以专注于特定页面 [英] Shrinking a UIScrollView to focus on a certain page

问题描述

我有一个带有水平分页的 UIScrollView -与天气应用类似.在某些情况下，我想防止用户水平滚动.只是简单地禁用滚动会有点刺耳-我宁愿复制滚动到最后一页的体验-允许进行一点滚动，但是由于没有更多内容，滚动视图会弹回.

I have a UIScrollView with horizontal pagination - similar to the weather app. Under certain circumstances, I want to prevent the user from scrolling horizontally. Simply disabling the scrolling is a little jarring - I would prefer to duplicate the experience of scrolling past the last page - a little scrolling is permitted, but since there is no more content, the scrollview bounces back.

我应该如何实施呢?我应该更改ScrollView的contentSize吗?如何设置分页，以便有效地存在一个页面"，但仍在左，右两边显示内容?

How might I go about implementing this? Should I be changing the contentSize of the ScrollView? How do I set up the pagination so that there is effectively one 'page' but there is still content displayed to the immediate left and right?

推荐答案

为了始终使 UIScrollView 弹跳，即使只有一页，也请添加以下行:

In order to always make the UIScrollView bounce, even with just one page, add the following line:

[self.scrollView setAlwaysBounceHorizontal:YES];

当然，除了我对缩小 contentSize 的评论.

In addition to my comment about shrinking the contentSize, of course.

好的，让我先解释一下我们想要实现的目标.用户正在 UIScrollView 中的页面之间愉快地滚动，突然，我们希望 UIScrollView 坚持当前页面，第一页.

OK, let me first explain want we want to achieve. The User is scrolling happily between the pages in the UIScrollView, and suddenly, we want the UIScrollView to stick to the current page, which may or may not be the first page.

我们的 UIScrollView 具有页面布局，每个页面均由一个 UIView 或其子类表示(它可能具有子视图):

Our UIScrollView has the pages laid out, with each page represented by a single UIView or it's subclasses (it may have subviews itself):

现在，要执行所说明的任务，下面是代码:

Now, to perform the task explained, here is the code:

CGFloat pageWidth = _scrollView.bounds.size.width;
int currentPage = (_scrollView.contentOffset.x / pageWidth);

[_scrollView setContentSize:CGSizeMake(pageWidth, _scrollView.contentSize.height)];
// move each page to the left:
for (UIView* page in _scrollView.subviews) {
    [page setFrame:CGRectOffset(page.frame, -currentPage * pageWidth, 0)];
}

注意::如果您具有复杂的视图层次结构，只需将其包装在一个 UIView 中，其边界大小等于 _scrollView.contentSize 包含所有页面.剩下的我留给读者练习(我一直想说xD)

NOTE: If you have a complicated view hierarchy, just wrap it in a UIView that has a bounds size equal to the _scrollView.contentSize with all the pages. The rest I leave it as an exercise for the reader (I always wanted to say that xD)

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