使用Autolayout在UIScrollView中动态UILabel高度

Question

我使用自动布局与UIScrollView来显示对象的某些属性。我从网络服务中免费下载这些信息。 scrollview有一个不变的宽度（因为我不想有垂直滚动行为），它的子视图用一组约束来尊重这个宽度，但是我不能动态增加UILabel的高度。

我的代码一切，我用viewDidLoad选择创建子视图...

- (void)viewDidLoad { 
    [super viewDidLoad]; 
    . 
    . 
    . 

    UILabel *descriptionLabel = [[UILabel alloc] initWithFrame:CGRectZero]; 
    descriptionLabel.translatesAutoresizingMaskIntoConstraints = NO; 
    descriptionLabel.numberOfLines = 0; 
    descriptionLabel.lineBreakMode = NSLineBreakByWordWrapping; 
    descriptionLabel.opaque = YES; 
    descriptionLabel.backgroundColor = [UIColor clearColor]; 
    descriptionLabel.textColor = [UIColor whiteColor]; 
    descriptionLabel.textAlignment = NSTextAlignmentRight; 
    descriptionLabel.font = [UIFont appetitoMediumItalicFontWithSize:15.0f]; 
    descriptionLabel.text = NSLocalizedStringFromTable(@"APT_DISH_DETAIL_DESCRIPTION", @"DishDetail", @"Etiqueta que contiene la descripción del platillo"); 
    [descriptionLabel setContentHuggingPriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisVertical]; 
    [self.detailContentScrollView addSubview:descriptionLabel]; 
    self.descriptionLabelS = descriptionLabel; 

    . 
    . 
    . 
} 

你可以看self.detailContentScrollView变量，这是从视图控制器的笔尖创建的IBOulet。

然后我用updateConstraints选择...

- (void)updateConstraints { 
[super updateConstraints]; 
// This dictionary has more variables, ok 
NSDictionary *viewsDict = @{@"dish_description_label": self.descriptionLabelS}; 
. 
. 
. 

[self.descriptionLabelS setContentHuggingPriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisVertical]; 
[self.detailContentScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[view1][dish_description_label]-[view2][view3][view4]-|" options:0 metrics:nil views:viewsDict]]; 

. 
. 
. 
} 

最后，当我收到的Web服务的信息，我送sizeToFit的UILabel从滚动视图选择和layoutIfNeeded。但我的UILabel从来没有调整自己的新内容。我究竟做错了什么？

Answer 1

UIScrollView的内容大小与自动布局动态更新，也许你只是必须执行以下操作

- (void) setupScroll 
{ 
    [_scrollView setTranslatesAutoresizingMaskIntoConstraints:NO]; 
    [_contentView setTranslatesAutoresizingMaskIntoConstraints:NO]; 

    [_scrollView addSubview:_contentView]; 

    NSArray *horizontal = [NSLayoutConstraint constraintsWithVisualFormat:@"|[_contentView]|" 
                    options:0 
                    metrics:nil 
                    views:NSDictionaryOfVariableBindings(_contentView)]; 
    NSArray *vertical = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_contentView]|" 
                   options:0 
                   metrics:nil 
                    views:NSDictionaryOfVariableBindings(_contentView)]; 

    [_scrollView addConstraints:horizontal]; 
    [_scrollView addConstraints:vertical]; 

    UIView *mainView = self.view; 
    horizontal = [NSLayoutConstraint constraintsWithVisualFormat:@"|[_contentView(==mainView)]|" 
                 options:0 
                 metrics:nil 
                  views:NSDictionaryOfVariableBindings(_contentView, mainView)]; 

    [mainView addConstraints:horizontal]; 
} 

哪里_contentView是您的UILabel（如果你把一个视图容器更复杂的视图层次）和自我。视图是控制器视图（或其他任何东西）。希望这有助于也是：iOS Autolayout with UIScrollview: Why does content view of scroll view not fill the scroll view? ....

也不要忘记建立你的UILabel preferredMaxLayoutWidth

干杯！

Answer 2

我有同样的问题。似乎有一个苹果的错误，所以多行文本需要一个两遍的方法来布局正确，它都依赖于属性preferredMaxLayoutWidth。

我结束了添加这两种方法的ScrollViewController：

- (void)viewDidLayoutSubviews 
{ 
    [super viewDidLayoutSubviews]; 
    [self performSelectorOnMainThread:@selector(adjustScrollContentSizeOnMainThread) withObject:nil waitUntilDone:NO]; 
} 

- (void)adjustScrollContentSizeOnMainThread 
{ 
    self.myLabel.preferredMaxLayoutWidth = self.myLabel.bounds.size.width; 
} 

我根据我对这个答案的解决方案：https://stackoverflow.com/a/13616052/2828256

Answer 3

如果你想与意见，使之：

• 添加约束高度> = [您想要的最小值]的UIScrollview，例如480

• 将UILabel添加到高度约束> = [minimum value you wan]例如460

像下面的图像：

，如果你需要使它编程

UIScrollView *scrollView= [UIScrollView new]; 
 
    scrollView.translatesAutoresizingMaskIntoConstraints = NO; 
 
    [self.view addSubview:scrollView]; 
 

 
    UILabel *scrollViewLabel = [[UILabel alloc] init]; 
 
    scrollViewLabel.numberOfLines = 0; 
 
    scrollViewLabel.translatesAutoresizingMaskIntoConstraints = NO; 
 
    [scrollView addSubview:scrollViewLabel]; 
 

 
    scrollViewLabel.text = @"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quisque ac urna ac ipsum sodales fermentum ornare quis tellus. Integer urna dolor, placerat ut pharetra sit amet, mattis a eros. Maecenas dapibus accumsan felis eget faucibus. Nulla rhoncus gravida neque, sed suscipit ex tempor quis. In sagittis sed enim ut posuere. Donec varius euismod rutrum. Pellentesque mauris sem, mollis id odio eu, maximus interdum elit. Mauris pharetra magna ut tortor lobortis sollicitudin. Cras volutpat porta facilisis. Praesent lacinia mi at volutpat accumsan. Sed eu cursus metus. Donec a convallis nunc. Curabitur tempus accumsan lacus vitae luctus. Sed non quam non leo condimentum congue. Nam dui ipsum, elementum in congue id, mollis ac mauris. Morbi finibus turpis quam, ut venenatis magna malesuada ac. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Aliquam erat volutpat. Curabitur nulla mi, aliquam faucibus blandit et, maximus eu libero. Duis semper, est posuere egestas interdum, quam nibh convallis odio, efficitur tempor purus arcu quis justo. Donec euismod feugiat urna in viverra. Sed vel tristique massa. Morbi in consequat sem. Nunc placerat lacus a mauris tempus porttitor. Fusce sed iaculis tortor, nec luctus ligula. Donec euismod metus mauris. Mauris sit amet euismod sapien. Praesent lobortis interdum ligula consequat viverra. Quisque et tortor mattis, congue dolor a, sagittis ligula. Phasellus in lacinia magna. Fusce vel placerat nisi. Maecenas egestas mattis lorem, vel tincidunt mauris eleifend et. In eu pulvinar nibh. Suspendisse ac suscipit orci. Suspendisse at lectus vel purus hendrerit lacinia at posuere sapien. Nunc auctor nisi eget nunc suscipit auctor. Donec fringilla odio lectus, quis porttitor nisl fermentum eget. Nam nunc purus, lobortis id sem porta, accumsan egestas quam. Integer blandit feugiat nunc ac scelerisque. Pellentesque vehicula, massa eget mollis aliquam, felis nulla posuere elit, at gravida elit diam id ligula. Suspendisse pharetra velit sed lacus scelerisque viverra. Maecenas volutpat non metus a interdum. In vitae vestibulum enim. Proin vitae libero non odio finibus pulvinar. In condimentum, sapien ac vehicula lobortis, dolor magna iaculis ex, in consectetur turpis orci eget justo. Suspendisse in lobortis justo, bibendum finibus lorem. Suspendisse ullamcorper diam eu elit sollicitudin, at tempus massa dignissim. In a ante rhoncus, porttitor tortor fermentum, molestie nunc. Phasellus mi dolor, vehicula sed sodales ut, sollicitudin ac ex. Praesent consequat, nunc sed posuere condimentum, risus ex malesuada nulla, sed faucibus velit elit ac risus. Ut venenatis ut nisl in hendrerit."; 
 

 

 
    /*** Auto Layout ***/ 
 

 
    NSDictionary *views = NSDictionaryOfVariableBindings(scrollView, scrollViewLabel); 
 

 
    NSArray *scrollViewLabelConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[scrollViewLabel(scrollView)]" options:0 metrics:nil views:views]; 
 
    [scrollView addConstraints:scrollViewLabelConstraints]; 
 

 
    scrollViewLabelConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[scrollViewLabel]|" options:0 metrics:nil views:views]; 
 
    [scrollView addConstraints:scrollViewLabelConstraints]; 
 

 
    NSArray *scrollViewConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[scrollView]-|" options:0 metrics:nil views:views]; 
 
    [self.view addConstraints:scrollViewConstraints]; 
 

 
    scrollViewConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[scrollView]-|" options:0 metrics:nil views:views]; 
 
    [self.view addConstraints:scrollViewConstraints];

Answer 4

这里是一个全面实施：

/*** Init the scrollview and the label ***/ 

UIScrollView *scrollView= [UIScrollView new]; 
scrollView.translatesAutoresizingMaskIntoConstraints = NO; 
[self.view addSubview:scrollView]; 

UILabel *scrollViewLabel = [[UILabel alloc] init]; 
scrollViewLabel.numberOfLines = 0; 
scrollViewLabel.translatesAutoresizingMaskIntoConstraints = NO; 
[scrollView addSubview:scrollViewLabel]; 

scrollViewLabel.text = @"Bacon ipsum dolor sit amet drumstick meatloaf filet mignon ham t-bone andouille meatball venison cow capicola jerky shankle shoulder ground round. Shank filet mignon pork chop ham hock, short ribs jerky prosciutto tongue porchetta. Biltong kevin strip steak tail jowl jerky boudin drumstick pastrami bresaola. Sirloin tail shoulder salami, hamburger beef doner turducken chuck boudin kielbasa sausage pork loin. Ball tip leberkas fatback, pork chop tail ham ribeye. Bresaola pancetta jerky beef kielbasa frankfurter, corned beef filet mignon ribeye tongue porchetta. Prosciutto short loin sirloin doner brisket jerky swine sausage bresaola chuck. Meatloaf pork chop ribeye bacon jerky turducken, andouille pork belly beef ribs ham hock leberkas. Andouille tri-tip capicola beef t-bone shank tenderloin turducken ball tip salami pork belly shankle. Kielbasa pastrami brisket, kevin spare ribs swine tail beef jerky venison filet mignon. Kevin leberkas ball tip, brisket bresaola chuck meatloaf beef doner drumstick hamburger capicola chicken. Tri-tip biltong drumstick pork prosciutto strip steak pastrami brisket shank hamburger flank tail cow. Pastrami beef ribs ribeye boudin spare ribs pork loin. Meatloaf tail pork belly strip steak doner. T-bone meatball pastrami, pork strip steak salami tail beef boudin leberkas. Venison t-bone fatback, pig brisket pork loin landjaeger turkey tri-tip biltong. Drumstick tri-tip hamburger boudin meatball pork pork chop short ribs chuck doner t-bone bacon frankfurter porchetta beef. Turkey cow meatball andouille pancetta, flank strip steak ham hock. Frankfurter corned beef rump turducken brisket, jerky short loin flank tri-tip ball tip ham hock swine spare ribs."; 


/*** Auto Layout ***/ 

NSDictionary *views = NSDictionaryOfVariableBindings(scrollView, scrollViewLabel); 

NSArray *scrollViewLabelConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[scrollViewLabel(scrollView)]" options:0 metrics:nil views:views]; 
[scrollView addConstraints:scrollViewLabelConstraints]; 

scrollViewLabelConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[scrollViewLabel]|" options:0 metrics:nil views:views]; 
[scrollView addConstraints:scrollViewLabelConstraints]; 

NSArray *scrollViewConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[scrollView]-|" options:0 metrics:nil views:views]; 
[self.view addConstraints:scrollViewConstraints]; 

scrollViewConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[scrollView]-|" options:0 metrics:nil views:views]; 
[self.view addConstraints:scrollViewConstraints]; 

有关详细说明：

https://arielelkin.github.io/articles/uilabel-plus-uiscrollview-plus-autolayout