150

我有一个用于缩放和滚动的UIImageView内部 a 。UIScrollView如果滚动视图的图像/内容大于滚动视图,则一切正常。但是,当图像变得小于滚动视图时,它会粘在滚动视图的左上角。我想让它保持居中,就像照片应用程序一样。

UIScrollView关于在较小时保持居中内容的任何想法或示例?

我正在使用 iPhone 3.0。

以下代码几乎可以工作。如果我在达到最小缩放级别后捏它,图像会返回到左上角。

- (void)loadView {
    [super loadView];

    // set up main scroll view
    imageScrollView = [[UIScrollView alloc] initWithFrame:[[self view] bounds]];
    [imageScrollView setBackgroundColor:[UIColor blackColor]];
    [imageScrollView setDelegate:self];
    [imageScrollView setBouncesZoom:YES];
    [[self view] addSubview:imageScrollView];

    UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"WeCanDoIt.png"]];
    [imageView setTag:ZOOM_VIEW_TAG];
    [imageScrollView setContentSize:[imageView frame].size];
    [imageScrollView addSubview:imageView];

    CGSize imageSize = imageView.image.size;
    [imageView release];

    CGSize maxSize = imageScrollView.frame.size;
    CGFloat widthRatio = maxSize.width / imageSize.width;
    CGFloat heightRatio = maxSize.height / imageSize.height;
    CGFloat initialZoom = (widthRatio > heightRatio) ? heightRatio : widthRatio;

    [imageScrollView setMinimumZoomScale:initialZoom];
    [imageScrollView setZoomScale:1];

    float topInset = (maxSize.height - imageSize.height) / 2.0;
    float sideInset = (maxSize.width - imageSize.width) / 2.0;
    if (topInset < 0.0) topInset = 0.0;
    if (sideInset < 0.0) sideInset = 0.0;
    [imageScrollView setContentInset:UIEdgeInsetsMake(topInset, sideInset, -topInset, -sideInset)];
}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
    return [imageScrollView viewWithTag:ZOOM_VIEW_TAG];
}

/************************************** NOTE **************************************/
/* The following delegate method works around a known bug in zoomToRect:animated: */
/* In the next release after 3.0 this workaround will no longer be necessary      */
/**********************************************************************************/
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale {
    [scrollView setZoomScale:scale+0.01 animated:NO];
    [scrollView setZoomScale:scale animated:NO];
    // END Bug workaround

    CGSize maxSize = imageScrollView.frame.size;
    CGSize viewSize = view.frame.size;
    float topInset = (maxSize.height - viewSize.height) / 2.0;
    float sideInset = (maxSize.width - viewSize.width) / 2.0;
    if (topInset < 0.0) topInset = 0.0;
    if (sideInset < 0.0) sideInset = 0.0;
    [imageScrollView setContentInset:UIEdgeInsetsMake(topInset, sideInset, -topInset, -sideInset)];
}
4

27 回答 27

232

我有非常简单的解决方案!您只需在放大 ScrollViewDelegate 时更新子视图(图像视图)的中心。如果缩放图像小于滚动视图,则调整 subview.center 否则中心为 (0,0)。

- (void)scrollViewDidZoom:(UIScrollView *)scrollView 
{
    UIView *subView = [scrollView.subviews objectAtIndex:0];

    CGFloat offsetX = MAX((scrollView.bounds.size.width - scrollView.contentSize.width) * 0.5, 0.0);
    CGFloat offsetY = MAX((scrollView.bounds.size.height - scrollView.contentSize.height) * 0.5, 0.0);

    subView.center = CGPointMake(scrollView.contentSize.width * 0.5 + offsetX, 
                                 scrollView.contentSize.height * 0.5 + offsetY);
}
于 2010-05-22T07:25:09.803 回答
60

@EvelynCordner 的答案是在我的应用程序中效果最好的答案。代码也比其他选项少得多。

如果有人需要,这是 Swift 版本:

func scrollViewDidZoom(_ scrollView: UIScrollView) {
    let offsetX = max((scrollView.bounds.width - scrollView.contentSize.width) * 0.5, 0)
    let offsetY = max((scrollView.bounds.height - scrollView.contentSize.height) * 0.5, 0)
    scrollView.contentInset = UIEdgeInsetsMake(offsetY, offsetX, 0, 0)
}
于 2016-03-23T05:57:01.237 回答
26

好的,在过去的两天里,我一直在断断续续地与这个作斗争,终于找到了一个非常可靠的(到目前为止......)解决方案,我认为我应该分享它并为其他人节省一些痛苦。:) 如果您确实发现此解决方案有问题,请大喊!

我基本上已经完成了其他人所拥有的:搜索 StackOverflow、Apple 开发者论坛,查看了 three20、ScrollingMadness、ScrollTestSuite 等的代码。我尝试扩大 UIImageView 框架,使用 UIScrollView 的偏移量和/或插图来自 ViewController 等,但没有什么效果很好(其他人也发现了)。

睡在上面之后,我尝试了几个不同的角度:

  1. 子类化 UIImageView 以便它动态地改变它自己的大小 - 这一点都不好用。
  2. 对 UIScrollView 进行子类化,使其动态更改自己的 contentOffset - 这对我来说似乎是赢家。

使用这个子类化 UIScrollView 方法,我将覆盖 contentOffset mutator,因此当图像缩放小于视口时它不会设置 {0,0} - 而是设置偏移量,以便图像将保持在视口中居中。到目前为止,它似乎总是有效。我已经用宽、高、小和大的图像检查了它,并且没有“工作但在最小缩放时捏会破坏它”的问题。

我已经将一个使用此解决方案的示例项目上传到 github,您可以在这里找到它:http: //github.com/nyoron/NYOBetterZoom

于 2010-04-14T14:28:48.380 回答
24

对于更适合使用自动布局的滚动视图的解决方案,请使用滚动视图的内容插入,而不是更新滚动视图的子视图的框架。

- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
    CGFloat offsetX = MAX((scrollView.bounds.size.width - scrollView.contentSize.width) * 0.5, 0.0);
    CGFloat offsetY = MAX((scrollView.bounds.size.height - scrollView.contentSize.height) * 0.5, 0.0);

    self.scrollView.contentInset = UIEdgeInsetsMake(offsetY, offsetX, 0.f, 0.f);
}
于 2015-07-15T04:45:10.330 回答
23

这段代码应该可以在大多数版本的 iOS 上运行(并且已经过测试可以在 3.1 以上版本上运行)。

它基于 photocoller 的 Apple WWDC 代码。

将以下内容添加到 UIScrollView 的子类中,并将 tileContainerView 替换为包含您的图像或图块的视图:

- (void)layoutSubviews {
    [super layoutSubviews];

    // center the image as it becomes smaller than the size of the screen
    CGSize boundsSize = self.bounds.size;
    CGRect frameToCenter = tileContainerView.frame;

    // center horizontally
    if (frameToCenter.size.width < boundsSize.width)
        frameToCenter.origin.x = (boundsSize.width - frameToCenter.size.width) / 2;
    else
        frameToCenter.origin.x = 0;

    // center vertically
    if (frameToCenter.size.height < boundsSize.height)
        frameToCenter.origin.y = (boundsSize.height - frameToCenter.size.height) / 2;
    else
        frameToCenter.origin.y = 0;

    tileContainerView.frame = frameToCenter;
}
于 2010-08-13T16:56:34.230 回答
21

目前我正在继承UIScrollView和覆盖setContentOffset:以调整基于contentSize. 它适用于捏合和程序缩放。

@implementation HPCenteringScrollView

- (void)setContentOffset:(CGPoint)contentOffset
{
    const CGSize contentSize = self.contentSize;
    const CGSize scrollViewSize = self.bounds.size;

    if (contentSize.width < scrollViewSize.width)
    {
        contentOffset.x = -(scrollViewSize.width - contentSize.width) / 2.0;
    }

    if (contentSize.height < scrollViewSize.height)
    {
        contentOffset.y = -(scrollViewSize.height - contentSize.height) / 2.0;
    }

    [super setContentOffset:contentOffset];
}

@end

除了短小精悍之外,这段代码还产生了比@Erdemus 解决方案更平滑的缩放。您可以在RMGallery演示中看到它的实际效果。

于 2014-03-21T12:06:47.383 回答
12

我花了一天时间解决这个问题,最终实现了scrollViewDidEndZooming:withView:atScale:如下:

- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale {
    CGFloat screenWidth = [[UIScreen mainScreen] bounds].size.width;
    CGFloat screenHeight = [[UIScreen mainScreen] bounds].size.height;
    CGFloat viewWidth = view.frame.size.width;
    CGFloat viewHeight = view.frame.size.height;

    CGFloat x = 0;
    CGFloat y = 0;

    if(viewWidth < screenWidth) {
        x = screenWidth / 2;
    }
    if(viewHeight < screenHeight) {
        y = screenHeight / 2 ;
    }

    self.scrollView.contentInset = UIEdgeInsetsMake(y, x, y, x);
}

这可确保当图像小于屏幕时,它周围仍有足够的空间,因此您可以将其定位到您想要的确切位置。

(假设你的 UIScrollView 包含一个 UIImageView 来保存图像)

本质上,它的作用是检查您的图像视图的宽度/高度是否小于屏幕的宽度/高度,如果是,则创建一个屏幕宽度/高度一半的插图(如果您希望图像走出屏幕边界)。

请注意,由于这是一个UIScrollViewDelegate方法,请不要忘记将其添加到视图控制器的声明中,以避免出现构建问题。

于 2011-01-25T11:31:03.683 回答
7

Apple 已向 iphone 开发者计划的所有成员发布了 2010 年 WWDC 会议视频。讨论的主题之一是他们如何创建照片应用程序!!!他们逐步构建了一个非常相似的应用程序,并免费提供了所有代码。

它也不使用私有 api。由于保密协议,我不能把任何代码放在这里,但这里是示例代码下载的链接。您可能需要登录才能获得访问权限。

http://connect.apple.com/cgi-bin/WebObjects/MemberSite.woa/wa/getSoftware?code=y&source=x&bundleID=20645

而且,这里是 iTunes WWDC 页面的链接:

http://insideapple.apple.com/redir/cbx-cgi.do?v=2&la=en&lc=&a=kGSol9sgPHP%2BtlWtLp%2BEP%2FnxnZarjWJglPBZRHd3oDbACudP51JNGS8KlsFgxZto9X%2BTsnqSbeUSWX0doe%2Fzv%2FN5XV55%2FomsyfRgFBysOnIVggO%2Fn2p%2BiweDK%2F%2FmsIXj

于 2010-06-20T19:51:05.217 回答
5

如果contentInset不需要其他任何东西,它可以用于居中滚动视图的内容。

class ContentCenteringScrollView: UIScrollView {

    override var bounds: CGRect {
        didSet { updateContentInset() }
    }

    override var contentSize: CGSize {
        didSet { updateContentInset() }
    }

    private func updateContentInset() {
        var top = CGFloat(0)
        var left = CGFloat(0)
        if contentSize.width < bounds.width {
            left = (bounds.width - contentSize.width) / 2
        }
        if contentSize.height < bounds.height {
            top = (bounds.height - contentSize.height) / 2
        }
        contentInset = UIEdgeInsets(top: top, left: left, bottom: top, right: left)
    }
}

如果这种方法的优点是您仍然可以使用contentLayoutGuide将内容放置在滚动视图中

scrollView.addSubview(imageView)
imageView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
    imageView.leadingAnchor.constraint(equalTo: scrollView.contentLayoutGuide.leadingAnchor),
    imageView.trailingAnchor.constraint(equalTo: scrollView.contentLayoutGuide.trailingAnchor),
    imageView.topAnchor.constraint(equalTo: scrollView.contentLayoutGuide.topAnchor),
    imageView.bottomAnchor.constraint(equalTo: scrollView.contentLayoutGuide.bottomAnchor)
])

或者只是在 Xcode 的 Interface Builder 中拖放内容。

于 2020-04-14T11:36:52.397 回答
2

我这样做的方法是在层次结构中添加一个额外的视图:

UIScrollView -> UIView -> UIImageView

给你与你UIView相同的纵横比UIScrollView,并以此为中心UIImageView

于 2009-08-24T19:05:57.970 回答
2

好的,这个解决方案对我有用。我有UIScrollView一个引用UIImageView它正在显示的子类。每当UIScrollView缩放时,都会调整 contentSize 属性。在设置器中,我UIImageView适当地缩放并调整其中心位置。

-(void) setContentSize:(CGSize) size{
CGSize lSelfSize = self.frame.size;
CGPoint mid;
if(self.zoomScale >= self.minimumZoomScale){
    CGSize lImageSize = cachedImageView.initialSize;
    float newHeight = lImageSize.height * self.zoomScale;

    if (newHeight < lSelfSize.height ) {
        newHeight = lSelfSize.height;
    }
    size.height = newHeight;

    float newWidth = lImageSize.width * self.zoomScale;
    if (newWidth < lSelfSize.width ) {
        newWidth = lSelfSize.width;
    }
    size.width = newWidth;
    mid = CGPointMake(size.width/2, size.height/2);

}
else {
    mid = CGPointMake(lSelfSize.width/2, lSelfSize.height/2);
}

cachedImageView.center = mid;
[super  setContentSize:size];
[self printLocations];
NSLog(@"zoom %f setting size %f x %f",self.zoomScale,size.width,size.height);
}

每次我将图像设置在UIScrollView我调整它的大小。滚动视图中的UIScrollView也是我创建的自定义类。

-(void) resetSize{
    if (!scrollView){//scroll view is view containing imageview
        return;
    }

    CGSize lSize = scrollView.frame.size;

    CGSize lSelfSize = self.image.size; 
    float lWidth = lSize.width/lSelfSize.width;
    float lHeight = lSize.height/lSelfSize.height;

    // choose minimum scale so image width fits screen
    float factor  = (lWidth<lHeight)?lWidth:lHeight;

    initialSize.height = lSelfSize.height  * factor;
    initialSize.width = lSelfSize.width  * factor;

    [scrollView setContentSize:lSize];
    [scrollView setContentOffset:CGPointZero];
    scrollView.userInteractionEnabled = YES;
}

使用这两种方法,我可以拥有一个与照片应用程序一样的视图。

于 2010-03-16T05:08:28.777 回答
2

只是快速批准的答案,但没有使用委托进行子类化

func centerScrollViewContents(scrollView: UIScrollView) {
    let contentSize = scrollView.contentSize
    let scrollViewSize = scrollView.frame.size;
    var contentOffset = scrollView.contentOffset;

    if (contentSize.width < scrollViewSize.width) {
        contentOffset.x = -(scrollViewSize.width - contentSize.width) / 2.0
    }

    if (contentSize.height < scrollViewSize.height) {
        contentOffset.y = -(scrollViewSize.height - contentSize.height) / 2.0
    }

    scrollView.setContentOffset(contentOffset, animated: false)
}

// UIScrollViewDelegate    
func scrollViewDidZoom(scrollView: UIScrollView) {
    centerScrollViewContents(scrollView)
}
于 2016-02-12T10:25:30.410 回答
2

我知道上面的一些答案是正确的,但我只是想给出一些解释,评论会让你明白我们为什么这样做。

当我第一次加载scrollView时,我写了以下代码使其居中,请注意我们contentOffset先设置,然后contentInset

    scrollView.maximumZoomScale = 8
    scrollView.minimumZoomScale = 1

    // set vContent frame
    vContent.frame = CGRect(x: 0,
                            y: 0  ,
                            width: vContentWidth,
                            height: vContentWidth)
    // set scrollView.contentSize
    scrollView.contentSize = vContent.frame.size

    //on the X direction, if contentSize.width > scrollView.bounds.with, move scrollView from 0 to offsetX to make it center(using `scrollView.contentOffset`)
    // if not, don't need to set offset, but we need to set contentInset to make it center.(using `scrollView.contentInset`)
    // so does the Y direction.
    let offsetX = max((scrollView.contentSize.width - scrollView.bounds.width) * 0.5, 0)
    let offsetY = max((scrollView.contentSize.height - scrollView.bounds.height) * 0.5, 0)
    scrollView.contentOffset = CGPoint(x: offsetX, y: offsetY)

    let topX = max((scrollView.bounds.width - scrollView.contentSize.width) * 0.5, 0)
    let topY = max((scrollView.bounds.height - scrollView.contentSize.height) * 0.5, 0)
    scrollView.contentInset = UIEdgeInsets(top: topY, left: topX, bottom: 0, right: 0)

然后,当我捏 vContent 时,我编写以下代码使其居中。

func scrollViewDidZoom(_ scrollView: UIScrollView) {
    //we just need to ensure that the content is in the center when the contentSize is less than scrollView.size.
    let topX = max((scrollView.bounds.width - scrollView.contentSize.width) * 0.5, 0)
    let topY = max((scrollView.bounds.height - scrollView.contentSize.height) * 0.5, 0)
    scrollView.contentInset = UIEdgeInsets(top: topY, left: topX, bottom: 0, right: 0)
}
于 2019-07-01T08:25:31.780 回答
1

您可以观察contentSizeUIScrollView 的属性(使用键值观察或类似方法),并在更改小于滚动视图的大小contentInset时自动调整。contentSize

于 2009-08-22T17:17:59.773 回答
1

一种将内容居中的优雅方式UISCrollView是这样。

将一个观察者添加到您的contentSizeUIScrollView,因此每次内容更改时都会调用此方法...

[myScrollView addObserver:delegate 
               forKeyPath:@"contentSize"
                  options:(NSKeyValueObservingOptionNew) 
                  context:NULL];

现在在你的观察者方法上:

- (void)observeValueForKeyPath:(NSString *)keyPath   ofObject:(id)object   change:(NSDictionary *)change   context:(void *)context { 

    // Correct Object Class.
    UIScrollView *pointer = object;

    // Calculate Center.
    CGFloat topCorrect = ([pointer bounds].size.height - [pointer viewWithTag:100].bounds.size.height * [pointer zoomScale])  / 2.0 ;
            topCorrect = ( topCorrect < 0.0 ? 0.0 : topCorrect );

    topCorrect = topCorrect - (  pointer.frame.origin.y - imageGallery.frame.origin.y );

    // Apply Correct Center.
    pointer.center = CGPointMake(pointer.center.x,
                                 pointer.center.y + topCorrect ); }
  • 你应该改变[pointer viewWithTag:100]. 替换为您的内容视图UIView

    • 还要更改imageGallery指向您的窗口大小。

每次他的大小改变时,这将纠正内容的中心。

注意:此内容不能很好地工作的唯一方法是使用UIScrollView.

于 2009-11-03T17:09:11.423 回答
1

您会发现 Erdemus 发布的解决方案确实有效,但是…… 在某些情况下,scrollViewDidZoom 方法没有被调用并且您的图像卡在左上角。一个简单的解决方案是在最初显示图像时显式调用该方法,如下所示:

[self scrollViewDidZoom: scrollView];

在许多情况下,您可能会两次调用此方法,但与本主题中的其他一些答案相比,这是一种更简洁的解决方案。

于 2011-09-07T01:13:06.223 回答
1

这是我对这个问题的解决方案,它适用于滚动视图中的任何类型的视图。

-(void)scrollViewDidZoom:(__unused UIScrollView *)scrollView 
    {
    CGFloat top;
    CGFloat left;
    CGFloat bottom;
    CGFloat right;

    if (_scrollView.contentSize.width < scrollView.bounds.size.width) {
        DDLogInfo(@"contentSize %@",NSStringFromCGSize(_scrollView.contentSize));

        CGFloat width = (_scrollView.bounds.size.width-_scrollView.contentSize.width)/2.0;

        left = width;
        right = width;


    }else {
        left = kInset;
        right = kInset;
    }

    if (_scrollView.contentSize.height < scrollView.bounds.size.height) {

        CGFloat height = (_scrollView.bounds.size.height-_scrollView.contentSize.height)/2.0;

        top = height;
        bottom = height;

    }else {
        top = kInset;
        right = kInset;
    }

    _scrollView.contentInset = UIEdgeInsetsMake(top, left, bottom, right);



  if ([self.tiledScrollViewDelegate respondsToSelector:@selector(tiledScrollViewDidZoom:)])
  {
        [self.tiledScrollViewDelegate tiledScrollViewDidZoom:self];
  }
}
于 2013-01-07T00:13:23.727 回答
1

这里有很多解决方案,但我会冒险将自己的解决方案放在这里。这有两个好处:它不会弄乱缩放体验,就像更新正在进行的图像视图框架一样,并且它尊重原始滚动视图插图(例如,在 xib 或情节提要中定义,以优雅地处理半透明工具栏等) .

首先,定义一个小助手:

CGSize CGSizeWithAspectFit(CGSize containerSize, CGSize contentSize) {
    CGFloat containerAspect = containerSize.width / containerSize.height,
            contentAspect = contentSize.width / contentSize.height;

    CGFloat scale = containerAspect > contentAspect
                    ? containerSize.height / contentSize.height
                    : containerSize.width / contentSize.width;

    return CGSizeMake(contentSize.width * scale, contentSize.height * scale);
}

要保留原始插图,定义字段:

UIEdgeInsets originalScrollViewInsets;

在 viewDidLoad 的某个地方填充它:

originalScrollViewInsets = self.scrollView.contentInset;

将 UIImageView 放入 UIScrollView (假设 UIImage 本身在 loadedImage 变量中):

CGSize containerSize = self.scrollView.bounds.size;
containerSize.height -= originalScrollViewInsets.top + originalScrollViewInsets.bottom;
containerSize.width -= originalScrollViewInsets.left + originalScrollViewInsets.right;

CGSize contentSize = CGSizeWithAspectFit(containerSize, loadedImage.size);

UIImageView *imageView = [[UIImageView alloc] initWithFrame:(CGRect) { CGPointZero, contentSize }];
imageView.autoresizingMask = UIViewAutoresizingNone;
imageView.contentMode = UIViewContentModeScaleAspectFit;
imageView.image = loadedImage;

[self.scrollView addSubview:imageView];
self.scrollView.contentSize = contentSize;

[self centerImageViewInScrollView];

scrollViewDidZoom: 来自 UIScrollViewDelegate 的滚动视图:

- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
    if (scrollView == self.scrollView) {
        [self centerImageViewInScrollView];
    }
}

最后,以自身为中心:

- (void)centerImageViewInScrollView {
    CGFloat excessiveWidth = MAX(0.0, self.scrollView.bounds.size.width - self.scrollView.contentSize.width),
            excessiveHeight = MAX(0.0, self.scrollView.bounds.size.height - self.scrollView.contentSize.height),
            insetX = excessiveWidth / 2.0,
            insetY = excessiveHeight / 2.0;

    self.scrollView.contentInset = UIEdgeInsetsMake(
            MAX(insetY, originalScrollViewInsets.top),
            MAX(insetX, originalScrollViewInsets.left),
            MAX(insetY, originalScrollViewInsets.bottom),
            MAX(insetX, originalScrollViewInsets.right)
    );
}

我还没有测试方向变化(即调整 UIScrollView 本身大小的正确反应),但修复它应该相对容易。

于 2013-03-20T19:40:41.147 回答
1

Apple 的 Photo Scroller 示例完全符合您的要求。把它放在你的 UIScrollView 子类中并将 _zoomView 更改为你的 UIImageView。

-(void)layoutSubviews{
  [super layoutSubviews];
  // center the zoom view as it becomes smaller than the size of the screen
  CGSize boundsSize = self.bounds.size;
  CGRect frameToCenter = self.imageView.frame;
  // center horizontally
  if (frameToCenter.size.width < boundsSize.width){
     frameToCenter.origin.x = (boundsSize.width - frameToCenter.size.width) / 2;
  }else{
    frameToCenter.origin.x = 0;
  }
  // center vertically
  if (frameToCenter.size.height < boundsSize.height){
     frameToCenter.origin.y = (boundsSize.height - frameToCenter.size.height) / 2;
  }else{
    frameToCenter.origin.y = 0;
  }
  self.imageView.frame = frameToCenter; 
}

Apple 的 Photo Scroller 示例代码

于 2013-05-01T17:35:10.130 回答
1

为了使动画流畅,设置

self.scrollview.bouncesZoom = NO;

并使用此功能(使用此答案中的方法找到中心)

- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale {
    [UIView animateWithDuration:0.2 animations:^{
        float offsetX = MAX((scrollView.bounds.size.width-scrollView.contentSize.width)/2, 0);
        float offsetY = MAX((scrollView.bounds.size.height-scrollView.contentSize.height)/2, 0);
        self.imageCoverView.center = CGPointMake(scrollView.contentSize.width*0.5+offsetX, scrollView.contentSize.height*0.5+offsetY);
    }];
}

这会产生弹跳效果,但事先不涉及任何突然的运动。

于 2015-03-18T03:40:38.637 回答
1

如果您的内部 imageView 具有初始特定宽度(例如 300)并且您只想将其宽度集中在小于其初始宽度的缩放上,这也可能对您有所帮助

 func scrollViewDidZoom(scrollView: UIScrollView){
    if imageView.frame.size.width < 300{
        imageView.center.x = self.view.frame.width/2
    }
  }
于 2016-09-26T14:06:34.153 回答
0

好的,我想我已经找到了一个很好的解决这个问题的方法。诀窍是不断重新调整imageView's框架。我发现这比不断调整contentInsetsor好得多contentOffSets。我不得不添加一些额外的代码来容纳纵向和横向图像。

这是代码:

- (void) scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale {

CGSize screenSize = [[self view] bounds].size;

if (myScrollView.zoomScale <= initialZoom +0.01) //This resolves a problem with the code not working correctly when zooming all the way out.
{
    imageView.frame = [[self view] bounds];
    [myScrollView setZoomScale:myScrollView.zoomScale +0.01];
}

if (myScrollView.zoomScale > initialZoom)
{
    if (CGImageGetWidth(temporaryImage.CGImage) > CGImageGetHeight(temporaryImage.CGImage)) //If the image is wider than tall, do the following...
    {
        if (screenSize.height >= CGImageGetHeight(temporaryImage.CGImage) * [myScrollView zoomScale]) //If the height of the screen is greater than the zoomed height of the image do the following...
        {
            imageView.frame = CGRectMake(0, 0, 320*(myScrollView.zoomScale), 368);
        }
        if (screenSize.height < CGImageGetHeight(temporaryImage.CGImage) * [myScrollView zoomScale]) //If the height of the screen is less than the zoomed height of the image do the following...
        {
            imageView.frame = CGRectMake(0, 0, 320*(myScrollView.zoomScale), CGImageGetHeight(temporaryImage.CGImage) * [myScrollView zoomScale]);
        }
    }
    if (CGImageGetWidth(temporaryImage.CGImage) < CGImageGetHeight(temporaryImage.CGImage)) //If the image is taller than wide, do the following...
    {
        CGFloat portraitHeight;
        if (CGImageGetHeight(temporaryImage.CGImage) * [myScrollView zoomScale] < 368)
        { portraitHeight = 368;}
        else {portraitHeight = CGImageGetHeight(temporaryImage.CGImage) * [myScrollView zoomScale];}

        if (screenSize.width >= CGImageGetWidth(temporaryImage.CGImage) * [myScrollView zoomScale]) //If the width of the screen is greater than the zoomed width of the image do the following...
        {
            imageView.frame = CGRectMake(0, 0, 320, portraitHeight);
        }
        if (screenSize.width < CGImageGetWidth (temporaryImage.CGImage) * [myScrollView zoomScale]) //If the width of the screen is less than the zoomed width of the image do the following...
        {
            imageView.frame = CGRectMake(0, 0, CGImageGetWidth(temporaryImage.CGImage) * [myScrollView zoomScale], portraitHeight);
        }
    }
    [myScrollView setZoomScale:myScrollView.zoomScale -0.01];
}
于 2009-10-04T01:50:40.177 回答
0

这是我目前的工作方式。它更好,但仍然不完美。尝试设置:

 myScrollView.bouncesZoom = YES; 

解决在 时视图不居中的问题minZoomScale

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
CGSize screenSize = [[self view] bounds].size;//[[UIScreen mainScreen] bounds].size;//
CGSize photoSize = [yourImage size];
CGFloat topInset = (screenSize.height - photoSize.height * [myScrollView zoomScale]) / 2.0;
CGFloat sideInset = (screenSize.width - photoSize.width * [myScrollView zoomScale]) / 2.0;

if (topInset < 0.0)
{ topInset = 0.0; }
if (sideInset < 0.0)
{ sideInset = 0.0; } 
[myScrollView setContentInset:UIEdgeInsetsMake(topInset, sideInset, -topInset, -sideInset)];
ApplicationDelegate *appDelegate = (ApplicationDelegate *)[[UIApplication sharedApplication] delegate];

CGFloat scrollViewHeight; //Used later to calculate the height of the scrollView
if (appDelegate.navigationController.navigationBar.hidden == YES) //If the NavBar is Hidden, set scrollViewHeight to 480
{ scrollViewHeight = 480; }
if (appDelegate.navigationController.navigationBar.hidden == NO) //If the NavBar not Hidden, set scrollViewHeight to 360
{ scrollViewHeight = 368; }

imageView.frame = CGRectMake(0, 0, CGImageGetWidth(yourImage)* [myScrollView zoomScale], CGImageGetHeight(yourImage)* [myScrollView zoomScale]);

[imageView setContentMode:UIViewContentModeCenter];
}

另外,我执行以下操作以防止图像在缩小后粘在侧面。

- (void) scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale {
myScrollView.frame = CGRectMake(0, 0, 320, 420);
 //put the correct parameters for your scroll view width and height above
}
于 2010-01-05T05:19:07.850 回答
0

只需禁用分页,它就可以正常工作:

scrollview.pagingEnabled = NO;
于 2014-03-21T05:26:37.780 回答
0

我有同样的问题。这是我解决的方法

此代码应作为以下结果调用scrollView:DidScroll:

CGFloat imageHeight = self.imageView.frame.size.width * self.imageView.image.size.height / self.imageView.image.size.width;
BOOL imageSmallerThanContent = (imageHeight < self.scrollview.frame.size.height) ? YES : NO;
CGFloat topOffset = (self.imageView.frame.size.height - imageHeight) / 2;

// If image is not large enough setup content offset in a way that image is centered and not vertically scrollable
if (imageSmallerThanContent) {
     topOffset = topOffset - ((self.scrollview.frame.size.height - imageHeight)/2);
}

self.scrollview.contentInset = UIEdgeInsetsMake(topOffset * -1, 0, topOffset * -1, 0);
于 2015-02-03T02:31:01.733 回答
0

虽然这个问题有点老了,但问题仍然存在。我在Xcode 7中通过将最上面的项目(在本例中topLabel为)。scrollViewIBOutlettopLabelbottomLabel

class MyViewController: UIViewController {

    @IBOutlet weak var scrollView: UIScrollView!
    @IBOutlet weak var topLabel: UILabel!
    @IBOutlet weak var bottomLabel: UILabel!
    @IBOutlet weak var toTopConstraint: NSLayoutConstraint!

    override func viewDidLayoutSubviews() {
        let heightOfScrollViewContents = (topLabel.frame.origin.y + topLabel.frame.size.height - bottomLabel.frame.origin.y)
        // In my case abs() delivers the perfect result, but you could also check if the heightOfScrollViewContents is greater than 0.
        toTopConstraint.constant = abs((scrollView.frame.height - heightOfScrollViewContents) / 2)
    }

    func refreshContents() {
        // Set the label's text …

        self.view.layoutIfNeeded()
    }
}
于 2015-10-05T10:20:07.860 回答
0

一个 Swift 版本,可以UIScrollView自己继承和 lauout 子视图。它工作得非常顺利。

import UIKit

class CenteringScrollView: UIScrollView {
    override func layoutSubviews() {
        super.layoutSubviews()

        if zoomScale < 1.0 {
            if let subview = self.subviews.first {
                subview.center.x = self.center.x
            }
        }
    }
}

于 2022-01-13T23:55:18.367 回答