UIScrollView的中心内容时，小(Center content of UIScrollVie

2019-06-18 18:40发布

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我有一个UIImageView一个内部UIScrollView ，我使用缩放和滚动。如果滚动视图的图像/内容大于滚动视图更大，一切工作正常。然而，当图像变得比滚动视图较小，它坚持滚动视图的左上角。我想保持它为中心，像照片应用程序。

关于保持的内容任何意见或例子UIScrollView时，它的体积更小的中心？

我与iPhone 3.0的工作。

下面的代码几乎工作。图像返回到左上角，如果我达到最低缩放级别后偷走。

- (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)];
}

Answer 1:

我有很简单的解决方案！所有你需要的是更新您的子视图（ImageView的）的中心，而在ScrollViewDelegate变焦。如果缩放图像小于滚动视图然后调整subview.center其他中心为（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);
}

Answer 2:

@ EvelynCordner的回答是，在我的应用效果最好的一个。少了很多的代码比其他的选择了。

以下是雨燕的版本，如果有人需要它：

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)
}

Answer 3:

好吧，我一直在争取这个在过去的两天和关闭，并具有终于来到，我想我应该分享并保存其他一些疼痛相当可靠（到目前为止...）解决方案。 :)如果你发现一个问题，这个解决方案，请留言！

我基本上是通过别人都已经：搜索StackOverflow上，苹果开发者论坛，看着为three20代码，ScrollingMadness，ScrollTestSuite，等我试过扩大UIImageView的框架，与UIScrollView的偏移和/或插图打从视图控制器等，但没有伟大的工作（如其他人已经发现了太）。

睡在它之后，我尝试了几个替代角度：

子类的UIImageView所以它改变了它动态自身的大小 - 这一点都没有很好地工作。
子类化的UIScrollView所以它改变了它自己的contentOffset动态 - 这是这似乎是对我来说是赢家之一。

有了这个子类UIScrollView的方法，我重写contentOffset突变所以它不是设置{0,0}当对图像进行缩放比视小 - 而不是它的设置偏移，使得图像将保持集中在视口中。到目前为止，它似乎总是工作。我已经与宽，高，细小及大图像检查，并没有“的作品，但在捏最小缩放打破它”的问题。

我上传一个例子项目github上使用此解决方案，您可以在这里找到： http://github.com/nyoron/NYOBetterZoom

Answer 4:

此代码应在iOS上的大多数版本的工作（并已经过测试，对工作3.1以上）。

它是基于对photoscoller苹果WWDC代码。

添加以下到您的UIScrollView的子类，以及包含图像或砖视图替换tileContainerView：

- (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;
}

Answer 5:

为了更好的适合使用自动布局滚动视图的解决方案，使用滚动视图内容的插图，而不是更新的滚动视图的子视图的帧。

- (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);
}

Answer 6:

目前我继承UIScrollView和压倒一切的setContentOffset:到偏移基于调整contentSize 。它的工作原理都与捏和程序化缩放。

@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

除了作为短期和甜蜜，这段代码产生比@Erdemus解决方案更加平滑变焦。你可以看到它在行动RMGallery演示。

Answer 7:

我花了一天这个问题的战斗，并最终实现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);
}

这保证了在图像比屏幕小，还是有它周围有足够的空间，以便您可以将其定位到您想要的确切地点。

（假设你的UIScrollView包含的UIImageView保存图像）

从本质上讲，这是什么做的是检查您的图像视图的宽度/高度是否是屏幕的宽度/高度小，如果是这样，创建屏幕的宽度/高度的一半插图（如果你想要的形象，你很可能使这个大走出屏幕边界的）。

请注意，因为这是一个UIScrollViewDelegate方法，不要忘了将它添加到您的视图控制器的声明，因此要避免让构建问题。

Answer 8:

苹果已经发布了2010年WWDC会议视频到iPhone开发计划的所有成员。其中一个讨论的主题是如何创建的照片应用程序！他们建立一步一个非常类似的应用程序的步骤，并已取得免费提供的所有代码。

它没有任何使用私有API。我不能把任何代码在这里，因为非公开协议，但这里是示例代码下载的链接。您可能需要登录才能访问。

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

而且，这里是iTunes的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

Answer 9:

好了，该解决方案为我工作。我有一个子类UIScrollView与该参考UIImageView它显示。每当UIScrollView缩放，该contentSize属性进行调整。这是我缩放的setter UIImageView适当，也可以调整它的中心位置。

-(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);
}

Evertime我设置在图像UIScrollView我调整其大小。的UIScrollView的滚动视图也是我创建了一个自定义类。

-(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;
}

这两种方法我能有行为就像照片应用程序的视图。

Answer 10:

你可以看contentSize的UIScrollView的财产（使用键-值观察或类似），并自动调整contentInset每当contentSize的变化小于滚动视图的大小。

Answer 11:

一个优雅的方式来中心的内容UISCrollView是这样的。

一个观察者添加到您的contentSize UIScrollView ，所以这种方法将被调用每次含量的变化...

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

现在，你的观察方法：

- (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] 通过您的内容视图替换UIView 。
- 也改变imageGallery指向你的窗口大小。

这将修正内容，每次他的身材变化的中心。

注：本内容不工作得非常好，唯一的方法是使用标准的缩放功能UIScrollView 。

Answer 12:

这是我解决这个问题这对任何类型的视图滚动视图中工作得很好。

-(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];
  }
}

Answer 13:

有有的是解决方案在这里，但我会冒险把这里我自己。这是很好的，原因有二：不乱变焦的经验，会做更新的进展图像视图帧，并且也尊重原滚动视图插图（比方说，在厦门国际银行或故事板定义为半透明的工具栏等的适度处理）。

首先，定义一个小帮手：

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);
}

要保留原来的插图，定义字段：

UIEdgeInsets originalScrollViewInsets;

而在某个地方填写viewDidLoad中它：

originalScrollViewInsets = self.scrollView.contentInset;

要放置的UIImageView到的UIScrollView（假设的UIImage本身是loadedImage VAR）：

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：从UIScrollViewDelegate该滚动视图：

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

一个最终，中心本身：

- (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)
    );
}

我没有测试的方向变化，但（对于调整的UIScrollView本身即适当的反应），但修为，应该是比较容易的。

Answer 14:

你会发现，张贴Erdemus解决方案的工作，但......有些情况下scrollViewDidZoom方法不被调用和图像粘贴到左上角。一个简单的解决方案是显式地调用的方法时最初显示的图像，如下所示：

[self scrollViewDidZoom: scrollView];

在很多情况下，你可以进行两次调用此方法，但是这是比一些本主题中的其他答案的一个清晰的解决方案。

Answer 15:

苹果的照片滚轮例不正是你所期待的。把这个在您的UIScrollView子类，并更改_zoomView是你的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; 
}

苹果的照片滚轮示例代码

Answer 16:

我这样做的方法是添加一个额外的视图成层次结构：

UIScrollView -> UIView -> UIImageView

给你UIView相同的宽高比为您UIScrollView ，和中心您UIImageView成。

Answer 17:

为了使动画流很好，设置

self.scrollview.bouncesZoom = NO;

和使用该功能（发现在使用该方法的中心此答案）

- (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);
    }];
}

这将创建弹跳效果，但事先不涉及任何突然的动作。

Answer 18:

就在迅速批准的答案，但没有使用委托继承

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)
}

Answer 19:

如果你内心的ImageView具有初始特定宽度（例如300），你只是要居中其宽度仅比变焦的初始宽度，这可能帮助你也较小。

 func scrollViewDidZoom(scrollView: UIScrollView){
    if imageView.frame.size.width < 300{
        imageView.center.x = self.view.frame.width/2
    }
  }

Answer 20:

下面是我在做这项工作目前的方式。这是更好，但还不够完善。尝试设置：

 myScrollView.bouncesZoom = YES;

与在当视图不居中解决问题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，我这样做，以防止缩小后坚持一个侧面的图像。

- (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
}

Answer 21:

好吧，我想我已经找到一个很好的解决了这个问题。诀窍是不断调整的imageView's框架。我觉得这个作品比不断调整要好得多contentInsets或contentOffSets 。我不得不添加一些额外的代码，以适应纵向和横向的图像。

下面的代码：

- (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];
}

Answer 22:

只是禁用分页，所以它会很好地工作：

scrollview.pagingEnabled = NO;

Answer 23:

我有同样的问题。这是我如何解决

此代码应该得到被称为结果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);

Answer 24:

虽然问题是有点老了，但仍存在问题。我解决了它在Xcode 7通过使最上层项目的垂直空间的限制（在这种情况下， topLabel ）到superViews（在scrollView ）顶部的IBOutlet ，然后其不断每次重新计算依据的滚动视图的高度含量的变化子视图（ topLabel和bottomLabel ）。

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()
    }
}

文章来源: Center content of UIScrollView when smaller

标签： ios objective-c cocoa-touch uiscrollview uiimageview

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