UIScrollView中的动态UILabel高度与Autolayout

Question

我使用autolayout UIScrollView来显示对象的一些属性.我从网络服务下载这个信息.scrollview具有恒定的宽度(因为我不希望有垂直滚动行为),并且其子视图使用一组约束来尊重此宽度,但我不能UILabel动态地增加其高度.

我编码所有内容,我使用viewDidLoad选择器来创建子视图...

- (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;

    .
    .
    .
}

您可以观察self.detailContentScrollView变量,这是IBOulet从视图控制器的笔尖创建的.

然后我使用updateConstraints选择器......

- (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,当我收到网络服务的信息时,我发送sizeToFit的UILabel选择器和layoutIfNeeded滚动视图.但我UILabel从来没有用新内容调整自己.我究竟做错了什么？

Answer 1

UIScrollView内容大小使用autolayout动态更新,也许您只需要执行以下操作

- (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];
}

_contentView是您的UILabel(如果您在视图容器上放置了更复杂的视图层次结构),self.view是控制器视图(或其他任何内容).希望这也有帮助:iOS Autolayout与UIScrollview:为什么滚动视图的内容视图不填充滚动视图？....

也别忘了建立你的 UILabel preferredMaxLayoutWidth

干杯!

Answer 2

如果你想用视图制作它:

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

• 使用高度约束> = [您想要的最小值]将滚动视图添加到UILabel,例如460

如下图所示:

如果你需要以编程方式进行

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];