Iphone 自动布局混乱：带有WebView和页眉/页脚视图的ScrollView的约束

为了说明我的问题，我创建了以下图形：

红场周围的黑色边框应该是iPhone屏幕。在内部，我们有一个红色的

UIScrollView

，它比屏幕高。事实上，它与上面显示为黄色的

UIWebView

一样高。

UIWebView

是

UIScrollView

的子视图，滚动被禁用。此外，我们有两个蓝色视图，我喜欢称之为页眉和页脚视图。它们也是

UIScrollView

的子视图，但不在可滚动范围内

我现在的问题是：如何为此配置自动布局约束

我已经使用检索了

UIWebView

高度，然后相应地更新了

UIScrollView

的

contentSize

。但是，这并不是一个好的解决方案，因为

UIWebView

的宽度不会对

UIScrollView

的宽度变化做出反应

我还成功地设置了标题视图的布局约束，如下所示（使用）：

但是，这样设置页脚视图的布局不起作用：

[changeView makeConstraints:^(MASConstraintMaker *make) {
    make.top.equalTo(scrollView.bottom)
    make.left.equalTo(@0);
    make.width.equalTo(scrollView.width);
    make.height.equalTo(@100);
}];

我觉得这不会太难，如果有人对自动布局更熟悉一些，我会非常感激。谢谢

在视觉格式语言（VFL）中，约束条件是：

[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-(-100)-[headerView(100)]" options:0 metrics:nil views:views]];
[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[footerView(100)]-(-100)-|" options:0 metrics:nil views:views]];
[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[headerView]|" options:0 metrics:nil views:views]];
[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[footerView]|" options:0 metrics:nil views:views]];

[footerView addConstraint:[NSLayoutConstraint constraintWithItem:footerView
                                                       attribute:NSLayoutAttributeHeight
                                                       relatedBy:NSLayoutRelationEqual
                                                          toItem:nil
                                                       attribute:NSLayoutAttributeNotAnAttribute
                                                      multiplier:1.0
                                                        constant:100.0]];

[scrollView addConstraint:[NSLayoutConstraint constraintWithItem:footerView
                                                       attribute:NSLayoutAttributeBottom
                                                       relatedBy:NSLayoutRelationEqual
                                                          toItem:scrollView
                                                       attribute:NSLayoutAttributeBottom
                                                      multiplier:1.0
                                                        constant:100.0]];

或者，如果要将

@“V:[footerView（100）]-（-100）-“

VFL替换为

constraintWithItem

调用，则它将是：

[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-(-100)-[headerView(100)]" options:0 metrics:nil views:views]];
[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[footerView(100)]-(-100)-|" options:0 metrics:nil views:views]];
[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[headerView]|" options:0 metrics:nil views:views]];
[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[footerView]|" options:0 metrics:nil views:views]];

[footerView addConstraint:[NSLayoutConstraint constraintWithItem:footerView
                                                       attribute:NSLayoutAttributeHeight
                                                       relatedBy:NSLayoutRelationEqual
                                                          toItem:nil
                                                       attribute:NSLayoutAttributeNotAnAttribute
                                                      multiplier:1.0
                                                        constant:100.0]];

[scrollView addConstraint:[NSLayoutConstraint constraintWithItem:footerView
                                                       attribute:NSLayoutAttributeBottom
                                                       relatedBy:NSLayoutRelationEqual
                                                          toItem:scrollView
                                                       attribute:NSLayoutAttributeBottom
                                                      multiplier:1.0
                                                        constant:100.0]];

我不能说你的Masorial实现为什么不起作用，因为我不熟悉它。但我会试试上面的一个，并确保

坦率地说，您描述了如何设置web视图的高度，我想知道您是否设置了web视图的高度约束（好），还是只是调整了

frame.size.height

值（坏）。但是您还没有分享如何设置web视图高度的详细信息，因此我无法进一步发表评论

无论如何，如果您有基于约束的问题，有两种有用的诊断技术。如果它仍然不工作，我会在模拟器上运行应用程序，暂停它，然后在

（lldb）

提示符下输入：

po [[UIWindow keyWindow] _autolayoutTrace]

您应该看到如下内容：

(lldb) po [[UIWindow keyWindow] _autolayoutTrace]
$0 = 0x0715d6e0 
*<UIWindow:0x758aae0>
|   *<UIView:0x71630f0>
|   |   *<UIScrollView:0x716a370>
|   |   |   *<HeaderView:0x716b860>
|   |   |   *<FooterView:0x716bbb0>
|   |   |   *<UIWebView:0x716c2b0>
|   |   |   |   <_UIWebViewScrollView:0x7176a30>
|   |   |   |   |   ...
|   |   |   |   |   <UIWebBrowserView:0x797fe00>
|   |   |   <UIImageView:0x75e1360>
|   |   |   <UIImageView:0x75e2a60>

(lldb) po [[UIWindow keyWindow] recursiveDescription]
$1 = 0x071c0ea0 <UIWindow: 0x758aae0; frame = (0 0; 320 568); autoresize = W+H; layer = <UIWindowLayer: 0x758b770>>
   | <UIView: 0x71630f0; frame = (0 20; 320 548); autoresize = RM+BM; layer = <CALayer: 0x7163180>>
   |    | <UIScrollView: 0x716a370; frame = (0 0; 320 548); clipsToBounds = YES; gestureRecognizers = <NSArray: 0x716b1d0>; layer = <CALayer: 0x716ad20>; contentOffset: {0, 16}>
   |    |    | <HeaderView: 0x716b860; frame = (0 -100; 320 100); layer = <CALayer: 0x716b910>>
   |    |    | <FooterView: 0x716bbb0; frame = (0 564; 320 100); layer = <CALayer: 0x716bee0>>
   |    |    | <UIWebView: 0x716c2b0; frame = (0 8; 320 548); layer = <CALayer: 0x716c360>>
   |    |    |    | <_UIWebViewScrollView: 0x7176a30; frame = (0 0; 320 548); clipsToBounds = YES; autoresize = H; gestureRecognizers = <NSArray: 0x7177000>; layer = <CALayer: 0x7176c80>; contentOffset: {0, 0}>
   |    |    |    |    | ...
   |    |    |    |    | <UIWebBrowserView: 0x797fe00; frame = (0 0; 1024 1754); gestureRecognizers = <NSArray: 0x7173260>; layer = <UIWebLayer: 0x716d7f0>>
   |    |    |    |    |    | ...
   |    |    | <UIImageView: 0x75e1360; frame = (1 540; 318 7); alpha = 0; opaque = NO; autoresize = TM; userInteractionEnabled = NO; layer = <CALayer: 0x75e2980>>
   |    |    | <UIImageView: 0x75e2a60; frame = (312 32.5; 7 530.5); alpha = 0; opaque = NO; autoresize = LM; userInteractionEnabled = NO; layer = <CALayer: 0x75e2b00>>

您应该看到如下内容：

(lldb) po [[UIWindow keyWindow] _autolayoutTrace]
$0 = 0x0715d6e0 
*<UIWindow:0x758aae0>
|   *<UIView:0x71630f0>
|   |   *<UIScrollView:0x716a370>
|   |   |   *<HeaderView:0x716b860>
|   |   |   *<FooterView:0x716bbb0>
|   |   |   *<UIWebView:0x716c2b0>
|   |   |   |   <_UIWebViewScrollView:0x7176a30>
|   |   |   |   |   ...
|   |   |   |   |   <UIWebBrowserView:0x797fe00>
|   |   |   <UIImageView:0x75e1360>
|   |   |   <UIImageView:0x75e2a60>

(lldb) po [[UIWindow keyWindow] recursiveDescription]
$1 = 0x071c0ea0 <UIWindow: 0x758aae0; frame = (0 0; 320 568); autoresize = W+H; layer = <UIWindowLayer: 0x758b770>>
   | <UIView: 0x71630f0; frame = (0 20; 320 548); autoresize = RM+BM; layer = <CALayer: 0x7163180>>
   |    | <UIScrollView: 0x716a370; frame = (0 0; 320 548); clipsToBounds = YES; gestureRecognizers = <NSArray: 0x716b1d0>; layer = <CALayer: 0x716ad20>; contentOffset: {0, 16}>
   |    |    | <HeaderView: 0x716b860; frame = (0 -100; 320 100); layer = <CALayer: 0x716b910>>
   |    |    | <FooterView: 0x716bbb0; frame = (0 564; 320 100); layer = <CALayer: 0x716bee0>>
   |    |    | <UIWebView: 0x716c2b0; frame = (0 8; 320 548); layer = <CALayer: 0x716c360>>
   |    |    |    | <_UIWebViewScrollView: 0x7176a30; frame = (0 0; 320 548); clipsToBounds = YES; autoresize = H; gestureRecognizers = <NSArray: 0x7177000>; layer = <CALayer: 0x7176c80>; contentOffset: {0, 0}>
   |    |    |    |    | ...
   |    |    |    |    | <UIWebBrowserView: 0x797fe00; frame = (0 0; 1024 1754); gestureRecognizers = <NSArray: 0x7173260>; layer = <UIWebLayer: 0x716d7f0>>
   |    |    |    |    |    | ...
   |    |    | <UIImageView: 0x75e1360; frame = (1 540; 318 7); alpha = 0; opaque = NO; autoresize = TM; userInteractionEnabled = NO; layer = <CALayer: 0x75e2980>>
   |    |    | <UIImageView: 0x75e2a60; frame = (312 32.5; 7 530.5); alpha = 0; opaque = NO; autoresize = LM; userInteractionEnabled = NO; layer = <CALayer: 0x75e2b00>>

---

谢谢你的回答，我现在已经设置好了。非常感谢调试命令，它们非常有用。