如何使用scrollRectToVisible滚动到图像的中心？

Question

我有缩放和平移一个UIScrollView。我想要的图像滚动到用户命令后的中心。我的问题是在计算是在图像的中心的框架的大小和位置。

有谁知道如何计算正确的帧为我的形象的中心？的问题是，如果是zoomScale不同帧的变化。

谢谢！

Answer 1

下面是也许有点更好的代码的情况下，任何人是需要; - ）

的UIScrollView + CenteredScroll.h：

@interface UIScrollView (CenteredScroll)

-(void)scrollRectToVisibleCenteredOn:(CGRect)visibleRect
                            animated:(BOOL)animated;

@end

的UIScrollView + CenteredScroll.m：

@implementation UIScrollView (CenteredScroll)

-(void)scrollRectToVisibleCenteredOn:(CGRect)visibleRect
                            animated:(BOOL)animated
{
  CGRect centeredRect = CGRectMake(visibleRect.origin.x + visibleRect.size.width/2.0 - self.frame.size.width/2.0,
                                   visibleRect.origin.y + visibleRect.size.height/2.0 - self.frame.size.height/2.0,
                                   self.frame.size.width,
                                   self.frame.size.height);
  [self scrollRectToVisible:centeredRect
                   animated:animated];
}

@end

Answer 2

基于丹尼尔Bauke答案

，我更新了他的代码，包括变焦倍数：

@implementation UIScrollView (jsCenteredScroll)

-(void)jsScrollRectToVisibleCenteredOn:(CGRect)visibleRect
                            animated:(BOOL)animated
{

    CGPoint center = visibleRect.origin;
    center.x += visibleRect.size.width/2;
    center.y += visibleRect.size.height/2;

    center.x *= self.zoomScale;
    center.y *= self.zoomScale;


    CGRect centeredRect = CGRectMake(center.x - self.frame.size.width/2.0,
                                     center.y - self.frame.size.height/2.0,
                                     self.frame.size.width,
                                     self.frame.size.height);
    [self scrollRectToVisible:centeredRect
                     animated:animated];
}

@end

Answer 3

private func centerScrollContent() {
    let x = (imageView.image!.size.width * scrollView.zoomScale / 2) - ((scrollView.bounds.width) / 2)
    let y = (imageView.image!.size.height * scrollView.zoomScale / 2) - ((scrollView.bounds.height) / 2)
    scrollView.contentOffset = CGPointMake(x, y)
}

Answer 4

好，得到它的工作。下面的代码柜面任何人是需要：

CGFloat tempy = imageView.frame.size.height;
CGFloat tempx = imageView.frame.size.width;
CGRect zoomRect = CGRectMake((tempx/2)-160, (tempy/2)-240, myScrollView.frame.size.width, myScrollView.frame.size.height);
[myScrollView scrollRectToVisible:zoomRect animated:YES];