Question

这是我在Stack Overflow上的第一篇文章，我是iOS初学者，所以请耐心等待我！

我有一个示例应用程序，其中我在父UIView（topView）中有三个UIViews（headerView，scrollViewContainer和bodyView），并且所有这些视图都是在代码中创建的。 topView被添加到在故事板中创建的UIScrollView（pageScrollView）。

pageScrollView正在填充iPhone的全屏，我使用了Autolayout。该应用程序仅包含ViewController.h和下面的伴随.m文件，以及Appdelegate.x。我想我开始使用单一视图应用程序模板。我正在使用iOS 6和Xcode 4.6，但我也试过4.5。

我尝试尽可能删除与此问题无关的其他代码。

问题：当应用程序启动时，它会正确显示其所有视图，并且scrollView允许按预期查看所有三个视图。但是在旋转到横向之后，scrollView以某种方式抵消了内容。例如：保持在顶部并且旋转=内容看起来没问题，但向下滚动一点并旋转使内容的顶部不显示。

我尝试过：我在网上寻求帮助，但我找不到任何对我有帮助的东西。我添加了各种数据的记录，如origin和contentSize，并尝试设置其中一些但没有任何成功。我还使用'po [[UIWindow keyWindow] _autolayoutTrace]'来确保约束条件正常。

我看不出我做错了什么。我的代码中是否有任何明显的缺失？

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

Answer 1

首先，您不需要在-updateViewConstraints方法中重新创建所有约束。你需要在这个地方更新它们。为实现您的目标，请执行以下操作：

仅创建一次约束。例如，在方法-setupConstraints中。并继续参考那些需要更新的内容。请参阅以下代码。
在方法-updateViewConstraints中，只需更新scrollViewContainer的topView高度和宽度约束和高度。

这里的ViewController.m应该是这样的：

#import "ViewController.h"

@interface ViewController ()
@property (nonatomic, strong) IBOutlet UIScrollView* pageScrollView;
@property (nonatomic, strong) NSLayoutConstraint* pictureHeightConstraint;
@property (nonatomic, strong) NSLayoutConstraint* topViewWidthConstraint;
@property (nonatomic, strong) NSLayoutConstraint* topViewHeightConstraint;

@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 setupConstraints];
}


- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
}

- (void)setupConstraints {
    // 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);

    // 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]-0-|" options:0 metrics:nil views:viewsDict]];
    [self.pageScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[topView]-0-|" options:0 metrics:nil views:viewsDict]];
    NSLayoutConstraint* topViewWidthConstraint = [NSLayoutConstraint constraintWithItem:topView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:newBounds.width];
    self.topViewWidthConstraint = topViewWidthConstraint;
    [topView addConstraint:self.topViewWidthConstraint];
    NSLayoutConstraint* topViewHeightConstraint = [NSLayoutConstraint constraintWithItem:topView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:topViewHeight];
    self.topViewHeightConstraint = topViewHeightConstraint;
    [topView addConstraint:self.topViewHeightConstraint];

    // 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]" options:0 metrics:nil views:viewsDict]];
    NSLayoutConstraint* pictureHeightConstraint = [NSLayoutConstraint constraintWithItem:scrollViewContainer attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:pictureScrollHeight];
    self.pictureHeightConstraint = pictureHeightConstraint;
    [scrollViewContainer addConstraint:self.pictureHeightConstraint];

    // 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]-0-|" options:0 metrics:nil views:viewsDict]];
}

- (void)updateViewConstraints
{
    [super updateViewConstraints];
    if ((newOrientation == UIDeviceOrientationLandscapeLeft) || (newOrientation == UIDeviceOrientationLandscapeRight)) {
        pictureScrollHeight = 300;
    } else {
        pictureScrollHeight = 203;
    }

    CGFloat topViewHeight = bodyViewHeight + 55 + pictureScrollHeight;
    self.pictureHeightConstraint.constant = pictureScrollHeight;
    self.topViewHeightConstraint.constant = topViewHeight;
    self.topViewWidthConstraint.constant = newBounds.width;
    [self.pageScrollView setNeedsUpdateConstraints];
}


- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
    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

ScrollView会根据添加到其中的子视图约束自动计算其内容大小。当然，它仅适用于自动布局环境。

Answer 2

检查自动调整大小的面具。

[self.pageScrollView setAutoresizingMask:UIViewAutoresizingFlexibleHeight];

Answer 3

看起来你在willRotateToInterfaceOrientation中没有对newBounds做任何事情。在获取新边界后，不应该调用updateView方法。

UIScrollView在旋转后仅显示部分UIView

3 个答案: