UIScrollView具有错误的contentSize和自动布局

Question

我在故事板中有一个iOS屏幕，如下所示：

如果我在模拟器中尝试这个，我就无法滚动到第二个UIView（我使用分页）。我知道这种情况正在发生，因为contentSize的宽度是320，但我不知道如何使用自动布局解决它并且我不知道如何使它在每个设备位置（横向，纵向）上工作。我需要在UIScrollView中只显示一个UIView。感谢。

Answer 1

它是可以解决的，应该适用于自动布局。

NSDictionary *views = NSDictionaryOfVariableBindings(scrollView, subview1, subview2);

// Constraint the scrollview frame within its parent
[parentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[scrollView]|" options:0 metrics: 0 views:viewsDictionary]];
[parentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[scrollView]|" options:0 metrics: 0 views:viewsDictionary]];

// Determine the scrollview's contentSize using its content
[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[subview1]|" options:0 metrics: 0 views:viewsDictionary]];
[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[subview1][subview2]|" options:0 metrics: 0 views:viewsDictionary]];
[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[subview2]|" options:0 metrics: 0 views:viewsDictionary]];

// Set the children width using the outer view
[parentView addConstraint:[NSLayoutConstraint constraintWithItem:subview1 attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:parentView attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0.0]];
[parentView addConstraint:[NSLayoutConstraint constraintWithItem:subview2 attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:parentView attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0.0]];

// Set the children height manually
[parentView addConstraint:[NSLayoutConstraint constraintWithItem:subview1 attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:80.0]];
[parentView addConstraint:[NSLayoutConstraint constraintWithItem:subview2 attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:80.0]];

告诉我你是否遇到问题。这种方法的优点是可以适应屏幕方向，屏幕尺寸，状态栏高度变化等。

上面的示例假设您要将子项的高度设置为固定高度（80像素）。为了使它垂直填满屏幕，你宁愿做与宽度相同的事情。

这也假设scrollview，subview1和subview2都将translatesAutoresizingMaskIntoConstraints属性设置为NO。

它还将不在滚动视图中垂直对齐子视图。如果你想这样做，你可以将它们中的每一个都放在他们自己的容器视图中，如下所示：

// Set the containers' width & height using the outer view
[parentView addConstraint:[NSLayoutConstraint constraintWithItem:containerview1 attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:parentView attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0.0]];
[parentView addConstraint:[NSLayoutConstraint constraintWithItem:containerview2 attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:parentView attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0.0]];

[parentView addConstraint:[NSLayoutConstraint constraintWithItem:containerview1 attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:parentView attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0.0]];
[parentView addConstraint:[NSLayoutConstraint constraintWithItem:containerview2 attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:parentView attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0.0]];

// Set the children height manually
[containerview1 addConstraint:[NSLayoutConstraint constraintWithItem:subview1 attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:80.0]];
[containerview2 addConstraint:[NSLayoutConstraint constraintWithItem:subview2 attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:80.0]];

// Align them vertically
[containerview1 addConstraint:[NSLayoutConstraint constraintWithItem:subview1 attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:containerview1 attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0.0]];
[containerview2 addConstraint:[NSLayoutConstraint constraintWithItem:subview2 attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:containerview2 attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0.0]];

// Set the width to equal that of their container
[containerview1 addConstraint:[NSLayoutConstraint constraintWithItem:subview1 attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:containerview1 attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0.0]];
[containerview2 addConstraint:[NSLayoutConstraint constraintWithItem:subview2 attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:containerview2 attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0.0]];

Answer 2

试试这样的事情：

[_scrollView setContentSize:CGSizeMake(640, _scrollView.frame.size.height)];

关于自动布局：有时候摆脱使用它们会更好。

考虑屏幕方向的代码：

float screenWidth = [UIScreen mainScreen].bounds.size.width;
[_scrollView setContentSize:CGSizeMake(screenWidth * 2, _scrollView.frame.size.height)];

要抓住设备旋转的那一刻，您应该在视图控制器中使用这样的方法：

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation
{
    // Remove current subviews

    for(UIView *subview in _scrollView.subviews)
    {
        [subview removeFromSuperview];
    }

    // Fill scroll view with subviews resized for screen size
    // ...
}