UIImageView在缩放后在PageControl中右侧被切断

Question

放大后我的图像在右侧被切断。如果我没有用cgrect make设置偏移，那么它不会被切断，但是我希望我的图像以屏幕为中心。我怎么能让我的图像居中，而不是在缩放后切断正确的部分？

- (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：这是我的看法层次

• 查看
  • mainScrollView
    • innerScrollFrame
      • pageScrollView
        • imageForZooming
    • innerScrollFrame
      • pageScrollView
        • imageForZooming

Answer 1

对于其他人在未来有同样的问题，我所做的是添加以下UIScrollViewDelegate协议：

- (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); 
} 

我发现这里的答案：Center content of UIScrollView when smaller

，使图像将放大后的中心而不是应用最初应用的偏移量。像魅力一样工作。现在当我缩放时，任何一个页面控件都不会切断我的图像，并且我可以将图像居中在视图的开头。