首页 \ 问答 \ 如果我在UITabBar之间切换UIViewController，则无法滚动回顶部(Can't scroll back to top, if I switch between UIViewController with UITabBar)

如果我在UITabBar之间切换UIViewController，则无法滚动回顶部(Can't scroll back to top, if I switch between UIViewController with UITabBar)

 我有我的UIScrollView问题，如果我点击一个标签栏项目切换到其他ViewController，然后回到ViewController与UIScrollView我不能回滚到顶部。 我必须在ViewControllers之间再次切换，然后正确显示UIScrollView的内容。 这个过程对于用户来说真的很不舒服。 这是我的代码：  
- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    [self becomeFirstResponder];  // View as first responder

    scrollView.scrollEnabled = YES;
    [scrollView setUserInteractionEnabled:YES];
    testLabel.text = @"there is a long, long text normally";   
}
 
 我没有特意设置contentSize，因为UIScrollView根据这个标签自动获得正确的高度。 我的问题是如果我向下滚动，然后切换到另一个ViewController，当我再次回到这个屏幕时，我不能再滚动到顶部。  
 一些进一步的信息：自动布局使用，层次结构是：ViewController - 查看 - UIScrollView - 标签，... 

I have an issue with my UIScrollView, if i click on a tab bar item to switch to an other ViewController and then go back to the ViewController with the UIScrollView i can't scroll back to the top. I have to switch again between ViewControllers and then the content in the UIScrollView is correctly shown. This procedure is really uncomfortable for the user. This is my code: 
- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    [self becomeFirstResponder];  // View as first responder

    scrollView.scrollEnabled = YES;
    [scrollView setUserInteractionEnabled:YES];
    testLabel.text = @"there is a long, long text normally";   
}
 
I didn't set the contentSize on purpose, because the UIScrollView automatically gets the correct height depending on this label. My Problem is if i scroll down and then switch to an other ViewController, when I'm coming back again to this screen I can't scroll up to the top anymore. 
Some further information: Auto Layout used, Hierarchy is: ViewController - View - UIScrollView - Label, ...

原文：https://stackoverflow.com/questions/14661606

更新时间：2023-11-04 13:11

最满意答案

 我无法找到一种简单的方法来使用内置的百里香对象/方法来完成此操作，但这会起作用（即使这有点痛苦）。  
 调节器  
@GetMapping
public String page(Map<String, Object> model) {
    .
    .
    DecimalFormat f = new DecimalFormat("#");
    f.setRoundingMode(RoundingMode.FLOOR);
    model.put("format", f);
    .
    .
}
 
 页  
<th:block th:with="n=${2.54}">
    <!-- outputs 2 -->
    <span th:text="${format.format(n)}" />
</th:block>

I can't find a simple way to do this with the built in thymeleaf objects/methods, but this will work (even if it's a little painful). 
Controller 
@GetMapping
public String page(Map<String, Object> model) {
    .
    .
    DecimalFormat f = new DecimalFormat("#");
    f.setRoundingMode(RoundingMode.FLOOR);
    model.put("format", f);
    .
    .
}
 
Page 
<th:block th:with="n=${2.54}">
    <!-- outputs 2 -->
    <span th:text="${format.format(n)}" />
</th:block>

如果我在UITabBar之间切换UIViewController，则无法滚动回顶部(Can't scroll back to top, if I switch between UIViewController with UITabBar)

最满意答案

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