Question

在处理旋转时，我在使用iPhone上的UIScrollView时遇到问题。我使用Apple的PageControl示例作为模型，但我自己在View中创建了scrollview。

1）当在默认纵向中加载时，滚动视图按预期工作，从左到右水平滚动

2）开箱即用时，旋转CW并重新初始化时，大多数侧面旋转，现在垂直向下旋转而不是所需的水平静止。似乎scrollview框架的宽度/高度不会改变，只是它自身的方向。

3）我尝试添加一些方向检测逻辑，以根据具有工作方向的方向正确调整和分页滚动视图，但前提是我将CCW旋转到横向。如果我去CW，它会从右侧开始向左滚动，但事情不起作用。

显然这是个hackish，所以有没有一种正确的方法来设置我的UIScrollview并使用旋转重新定位它，所以它总是从左向右滚动？


- (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];
}

Answer 1

你没有改变你的滚动视图的contentSize，所以当它旋转时，它不知道它比它更高更宽。

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

最后，只是一个视觉事物，使用willRotateToInterfaceOrientation：持续时间在眼睛上更好一些，并且用户永远不会感觉到变化，因为它几乎与旋转同时发生。

使用分页旋转UIScrollView的问题

1 个答案: