ios - 缩放后 UIImageView 在 PageControl 的右侧被截断

Question

放大后我的图像在右侧被切断。如果我不使用 cgrect make 设置偏移量，那么它不会被切断，但我希望我的图像在屏幕上居中。我怎样才能让我的图像居中并且在缩放后不切断正确的部分？

- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.

self.view.backgroundColor = [UIColor grayColor];

UIScrollView *mainScrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
mainScrollView.pagingEnabled = YES;
mainScrollView.showsHorizontalScrollIndicator = NO;
mainScrollView.showsVerticalScrollIndicator = NO;

CGRect innerScrollFrame = mainScrollView.bounds;

for (NSInteger i = 0; i < 2; i++) {
    UIImageView *imageForZooming = [[UIImageView alloc] initWithImage:[UIImage imageNamed:[NSString stringWithFormat:@"page%d", i + 1]]];
    imageForZooming.tag = VIEW_FOR_ZOOM_TAG;
    imageForZooming.frame = CGRectMake(50, 0, imageForZooming.bounds.size.width, imageForZooming.bounds.size.height);

    UIScrollView *pageScrollView = [[UIScrollView alloc] initWithFrame:innerScrollFrame];
    pageScrollView.minimumZoomScale = 0.5f;
    pageScrollView.maximumZoomScale = 1.0f;
    pageScrollView.contentSize = imageForZooming.bounds.size;
    pageScrollView.delegate = self;
    [pageScrollView addSubview:imageForZooming];

    [mainScrollView addSubview:pageScrollView];

    if (i < 1) {
        innerScrollFrame.origin.x += innerScrollFrame.size.width;
    }

    pageScrollView.zoomScale = 0.5f;
}

mainScrollView.contentSize = CGSizeMake(innerScrollFrame.origin.x + innerScrollFrame.size.width, mainScrollView.bounds.size.height);

[self.view addSubview:mainScrollView];
}

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

编辑:这是我的 View 层次结构

• 查看
  • 主 ScrollView
    • innerScrollFrame
      • 页面 ScrollView
        • 图像缩放
    • innerScrollFrame
      • 页面 ScrollView
        • 图像缩放

Answer 1

对于以后遇到同样问题的其他人，我所做的是添加以下 UIScrollViewDelegate 协议(protocol):

- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
    UIView *subView = [scrollView.subviews objectAtIndex:0];
    CGFloat offsetX = (scrollView.bounds.size.width > scrollView.contentSize.width) ? (scrollView.bounds.size.width - scrollView.contentSize.width) * 0.5 : 0.0;
    CGFloat offsetY = (scrollView.bounds.size.height > scrollView.contentSize.height) ? (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);
}

我在这里找到了答案:Center content of UIScrollView when smaller

这样图像在缩放后会居中，而不是应用最初应用的偏移量。工作起来很有魅力。现在，当我缩放时，我的图像在任一页面控件上都不会被截断，而且我可以将图像居中显示在 View 的开头。