这是我在 Stack Overflow 上的第一篇文章，我是 iOS 初学者，所以请多多包涵！
我有一个示例应用程序，其中在父 UIView（topView）中有三个 UIView（headerView、scrollViewContainer 和 bodyView），并且所有这些视图都是在代码中创建的。topView 被添加到在 storyboard 中创建的 UIScrollView (pageScrollView)。
pageScrollView 正在填充 iPhone 的全屏，我使用了 Autolayout。该应用程序仅包含下面所示的 ViewController.h 和伴随的 .m 文件，以及 Appdelegate.x。我想我是从单一视图应用程序模板开始的。我使用的是 iOS 6 和 Xcode 4.6，但我也尝试了 4.5。
我试图尽可能多地删除与此问题无关的其他代码。
问题：当应用程序启动时，它会正确显示所有视图，并且 scrollView 允许按预期查看所有三个视图。但是在旋转到横向后，scrollView 会以某种方式偏移内容。例如：留在顶部并旋转 = 内容看起来不错，但向下滚动一点并旋转会使内容的顶部不显示。
我尝试过的：我在网上搜索过帮助，但没有找到任何似乎对我有帮助的东西。我已经添加了各种数据的日志记录，例如 origin 和 contentSize，并且还尝试设置其中一些但没有成功。我还使用了 'po [[UIWindow keyWindow] _autolayoutTrace]' 来确保约束正常。
我看不出我做错了什么。我的代码中是否缺少任何明显的东西？
提前致谢！
这是 ViewController.m：
#import "ViewController.h"
@interface ViewController ()
{
UIView *topView;
UIView *headerView;
UIView *bodyView;
UIView *scrollViewContainer;
UIInterfaceOrientation newOrientation;
CGFloat bodyViewHeight;
CGSize newBounds;
float pictureScrollHeight;
}
@end
@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
newBounds = [self sizeInOrientation:[UIApplication sharedApplication].statusBarOrientation];
newOrientation = [UIApplication sharedApplication].statusBarOrientation;
bodyViewHeight = 1200; // The height of the body view varies in size depending on orientation
self.pageScrollView.translatesAutoresizingMaskIntoConstraints = NO;
topView = [[UIView alloc] init];
[topView setBackgroundColor:[UIColor clearColor]];
topView.translatesAutoresizingMaskIntoConstraints = NO;
[self.pageScrollView addSubview:topView];
headerView = [[UIView alloc] init];
[headerView setBackgroundColor:[UIColor redColor]];
headerView.translatesAutoresizingMaskIntoConstraints = NO;
[topView addSubview:headerView];
scrollViewContainer = [[UIView alloc] init];
[scrollViewContainer setBackgroundColor:[UIColor blueColor]];
scrollViewContainer.translatesAutoresizingMaskIntoConstraints = NO;
[topView addSubview:scrollViewContainer];
bodyView = [[UIView alloc] init];
[bodyView setBackgroundColor:[UIColor greenColor]];
bodyView.translatesAutoresizingMaskIntoConstraints = NO;
[topView addSubview:bodyView];
[self updateViewConstraints];
}
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
}
- (void)updateViewConstraints
{
[super updateViewConstraints];
// Remove old constraints
[self.view removeConstraints:self.view.constraints];
[self.pageScrollView removeConstraints:self.pageScrollView.constraints];
[topView removeConstraints:topView.constraints];
[scrollViewContainer removeConstraints:scrollViewContainer.constraints];
if ((newOrientation == UIDeviceOrientationLandscapeLeft) || (newOrientation == UIDeviceOrientationLandscapeRight)) {
pictureScrollHeight = 300;
} else {
pictureScrollHeight = 203;
}
[headerView setNeedsDisplay];
[bodyView setNeedsDisplay];
CGFloat topViewHeight = bodyViewHeight + 55 + pictureScrollHeight;
//self.pageScrollView = _pageScrollView
NSDictionary *viewsDict = NSDictionaryOfVariableBindings(_pageScrollView, topView, headerView, bodyView, scrollViewContainer);
NSDictionary *metricsDict = @{@"topViewHeight": [NSNumber numberWithFloat:topViewHeight],
@"newBoundsWidth": [NSNumber numberWithFloat:newBounds.width],
@"pictureScrollHeight": [NSNumber numberWithFloat:pictureScrollHeight],
@"bodyViewHeight": [NSNumber numberWithFloat:bodyViewHeight]};
// pageScrollView - child to self.view
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[_pageScrollView]-0-|" options:0 metrics:nil views:viewsDict]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[_pageScrollView]-0-|" options:0 metrics:nil views:viewsDict]];
// topView - child to pageScrollView
[self.pageScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[topView(newBoundsWidth)]-0-|" options:0 metrics:metricsDict views:viewsDict]];
[self.pageScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[topView(topViewHeight)]-0-|" options:0 metrics:metricsDict views:viewsDict]];
// headerView - child to topView
[topView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[headerView]-0-|" options:0 metrics:nil views:viewsDict]];
[topView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[headerView(55.0)]" options:0 metrics:nil views:viewsDict]];
// scrollViewContainer - child to topView
[topView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[scrollViewContainer]-0-|" options:0 metrics:nil views:viewsDict]];
[topView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[headerView]-0-[scrollViewContainer(pictureScrollHeight)]" options:0 metrics:metricsDict views:viewsDict]];
// bodyView - child to topView
[topView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[bodyView]-0-|" options:0 metrics:nil views:viewsDict]];
[topView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[scrollViewContainer]-0-[bodyView(bodyViewHeight)]-0-|" options:0 metrics:metricsDict views:viewsDict]];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
newOrientation = toInterfaceOrientation;
newBounds = [self sizeInOrientation:toInterfaceOrientation];
}
-(CGSize) sizeInOrientation:(UIInterfaceOrientation)orientation
{
CGSize size = [UIScreen mainScreen].bounds.size;
UIApplication *application = [UIApplication sharedApplication];
if (UIInterfaceOrientationIsLandscape(orientation))
{
size = CGSizeMake(size.height, size.width);
}
if (application.statusBarHidden == NO)
{
size.height -= MIN(application.statusBarFrame.size.width, application.statusBarFrame.size.height);
}
return size;
}
@end