使用分页旋转 UIScrollView 的问题

Posted 2023-03-14

【中文标题】使用分页旋转 UIScrollView 的问题

【英文标题】：problems rotating UIScrollView with paging

【发布时间】：2010-08-29 17:21:21

【问题描述】：

在处理旋转时，我在 iPhone 上使用 UIScrollView 时遇到问题。我使用 Apple 的 PageControl 示例作为模型，但我自己在 View 中创建滚动视图。

1) 在默认纵向加载时，滚动视图按预期工作，从左到右水平滚动 2) 开箱即用，当顺时针旋转并重新初始化时，大部分情况下会将其侧向旋转，现在它垂直向下旋转，而不是所需的水平静止。似乎滚动视图框架的宽度/高度没有改变，只是自身的方向。 3) 我尝试添加一些方向检测逻辑，以根据方向正确调整滚动视图的大小和分页，但前提是我将 CCW 旋转为横向。如果我去 CW，它会从右边开始，然后滚动到左边，事情就不起作用了。

很明显，这越来越不自然了，那么有没有合适的方法来设置我的 UIScrollview 并通过旋转重新初始化它，使其始终从左到右滚动？

- (void)loadView [self setupPage]; -(void) setupPage // lazy init view controllers NSMutableArray *controllers = [[NSMutableArray alloc] init]; for (unsigned i = 0; i = kNumberOfPages) return; // replace the placeholder if necessary MyViewController *controller = [viewControllers objectAtIndex:page]; if ((NSNull *)controller == [NSNull null]) controller = [[MyViewController alloc] initWithPageNumber:page]; [viewControllers replaceObjectAtIndex:page withObject:controller]; [controller release]; // add the controller's view to the scroll view if (nil == controller.view.superview) CGRect frame = scrollView.frame; int x = 0; int y = 0; UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation]; if(orientation == UIDeviceOrientationLandscapeLeft || orientation == UIDeviceOrientationLandscapeRight) x = 0; y = frame.size.height * page; else x = frame.size.width * page; y = 0; frame.origin.x = x; frame.origin.y = y; controller.view.frame = frame; [scrollView addSubview:controller.view]; - (void)scrollViewDidScroll:(UIScrollView *)sender // We don't want a "feedback loop" between the UIPageControl and the scroll delegate in // which a scroll event generated from the user hitting the page control triggers updates from // the delegate method. We use a boolean to disable the delegate logic when the page control is used. if (pageControlUsed) // do nothing - the scroll was initiated from the page control, not the user dragging return; // Switch the indicator when more than 50% of the previous/next page is visible CGFloat pageWidth = scrollView.frame.size.width; int offset = 0; UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation]; if(orientation == UIDeviceOrientationLandscapeLeft || orientation == UIDeviceOrientationLandscapeRight) pageWidth = scrollView.frame.size.height; offset = scrollView.contentOffset.y; else pageWidth = scrollView.frame.size.width; offset = scrollView.contentOffset.x ; //CGFloat pageWidth = scrollView.frame.size.width; int page = floor((offset - pageWidth / 2) / pageWidth) + 1; pageControl.currentPage = page; // load the visible page and the page on either side of it (to avoid flashes when the user starts scrolling) [self loadScrollViewWithPage:page - 1]; [self loadScrollViewWithPage:page]; [self loadScrollViewWithPage:page + 1]; // A possible optimization would be to unload the views+controllers which are no longer visible // At the begin of scroll dragging, reset the boolean used when scrolls originate from the UIPageControl - (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView pageControlUsed = NO; // At the end of scroll animation, reset the boolean used when scrolls originate from the UIPageControl - (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView pageControlUsed = NO; - (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation [self setupPage];

【参考方案1】：

你没有改变你的滚动视图的 contentSize，所以当它旋转时它不知道它的宽度大于它的高度。

另外，作为快捷方式，每个 VC 都已经设置了 interfaceOrientation 属性，并且内置了检测方向的函数：UIInterfaceOrientationIsPortrait(self.interfaceOrientation) 和 UIInterfaceOrientationIsLandscape(self.interfaceOrientation)。

最后，只是视觉上的东西，使用 willRotateToInterfaceOrientation:duration 对眼睛来说更好一些，并且用户永远不会感知到变化，因为它几乎与旋转同时发生。