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我有一个应用程序，其中包含一个带有多个表格视图的滚动视图。每个表视图都是从另一个视图控制器加载的。它是从 Apple 的 PageControl 示例应用程序构建的。我的目标是让它像苹果的天气应用一样工作。

我的一切工作都很好。所有内容都完美加载，左右滚动显示所有正确的表格视图及其相关数据。我有一个按钮，单击它会打开另一个视图，允许您编辑每个项目，就像天气应用程序一样，您可以在其中添加新城市、删除它或移动它。

我遇到的问题是当用户完成编辑项目时如何更新滚动视图。想象一下，在 PageControl 应用程序中能够删除第 5 页或将第 4 页移动到位置 #1，等等。

我没有粘贴任何代码，因为：1）它与 PageControl 应用程序中的代码相同；2）我还没想好从哪里开始。希望这里有人可以帮助我。

谢谢。

更新：（2010 年 3 月 5 日美国东部标准时间上午 3:18）

好的，所以我已经为此工作了一段时间。我能够在 mainView 中调用一个方法来更新他的滚动视图。代码看起来有点笨拙，但它确实有效！我真的不喜欢该代码，因为我最终使用了一次属性，并且我无法再次设置它，因为我得到一个错误objc[10801]: FREED(id): message release sent to freed object=0x3f4a490。在我看来，该对象似乎已被释放？如果是这样，我不知道如何，因为我只在dealloc. dealloc从未被调用（我NSLog检查了）所以我不知道发生了什么。

代码：初始代码与 Apple 的 PageControl 示例应用程序中的代码相同： 

- (void)viewDidLoad {
    [super viewDidLoad];
    appDel = (iBarryAppDelegate *)[[UIApplication sharedApplication] delegate];
    managedObjectContext = appDel.managedObjectContext;
    NSMutableArray *controllers = [[NSMutableArray alloc] init];
    for (unsigned i = 0; i < numberOfPages; i++)
    {
        [controllers addObject:[NSNull null]];
    }
    self.viewControllers = controllers;
    [controllers release];
    scrollView.pagingEnabled = YES;
    scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * numberOfPages, scrollView.frame.size.height);
    scrollView.showsHorizontalScrollIndicator = NO;
    scrollView.showsVerticalScrollIndicator = NO;
    scrollView.scrollsToTop = NO;
    scrollView.delegate = self;
    pageControl.numberOfPages = numberOfPages;
    pageControl.currentPage = 0;
    //I end up commenting out all the method calls to
    //[self loadScrollViewWithPage:xxx]; and load all the views at once.
    //I know I should be lazy-loading here , but Scrolling is much 
    //faster if I load them all at once, instead 
    //of when they are about to be viewed.
    for (unsigned i = 0; i < numberOfPages; i++)
    {
        [self loadScrollViewWithPage:i];
    }
}
- (void)loadMainController:(int)page
{
    MainViewController *controller = [viewControllers objectAtIndex:page];
    if ((NSNull *)controller == [NSNull null])
    {
        controller = [[MainViewController alloc] initWithPageNumber:page];
        [viewControllers replaceObjectAtIndex:page withObject:controller];
        [controller release];
    }
    if (nil == controller.view.superview)
    {
        CGRect frame = scrollView.frame;
        frame.origin.x = frame.size.width * page;
        frame.origin.y = 0;
        controller.view.frame = frame;
        [scrollView addSubview:controller.view];
    }
}
- (void)loadScrollViewWithPage:(int)page
{
    if (page < 0) return;
    if (page >= numberOfPages) return;
    [self loadMainController:page];
}
- (void)scrollViewDidScroll:(UIScrollView *)sender
{
    if (pageControlUsed)
    {
        return;
    }
    CGFloat pageWidth = scrollView.frame.size.width;
    int page = floor((scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
    pageControl.currentPage = page;
//  [self loadScrollViewWithPage:page - 1];
//  [self loadScrollViewWithPage:page];
//  [self loadScrollViewWithPage:page + 1];
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    pageControlUsed = NO;
}
- (IBAction)changePage:(id)sender
{
    int page = pageControl.currentPage;
//  [self loadScrollViewWithPage:page - 1];
//  [self loadScrollViewWithPage:page];
//  [self loadScrollViewWithPage:page + 1];
    CGRect frame = scrollView.frame;
    frame.origin.x = frame.size.width * page;
    frame.origin.y = 0;
    [scrollView scrollRectToVisible:frame animated:YES];
    pageControlUsed = YES;
}

然后我有我的代码来刷新滚动视图。我所做的是删除所有子视图并再次加载它们。我永远不会有超过 13 个子视图，不确定将它们全部删除并重新创建它们是一个好主意还是坏主意。

- (void)reloadDataNow
{
    for(UIView *subview in [scrollView subviews]) {
            [subview removeFromSuperview];
            NSLog(@"removed a suview");
    }
    [self loadData]; //this method fetches which data will be 
    //in the scrollView. It reloads the number of pages based 
    //on the return result and an NSMutableArray where I store 
    //data to pass to the views that will appear in the scrollView
    NSMutableArray *controllers = [[NSMutableArray alloc] init];
    for (unsigned i = 0; i < numberOfPages; i++)
    {
        [controllers addObject:[NSNull null]];
    }
    scrollView.pagingEnabled = YES;
    scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * numberOfPages, scrollView.frame.size.height);
    scrollView.showsHorizontalScrollIndicator = NO;
    scrollView.showsVerticalScrollIndicator = NO;
    scrollView.scrollsToTop = NO;
    scrollView.delegate = self;
    pageControl.numberOfPages = numberOfPages;
    pageControl.currentPage = 0;
    for (unsigned i = 0; i < numberOfPages; i++)
    {
        MainViewController *controller = [controllers objectAtIndex:i];
        if ((NSNull *)controller == [NSNull null])
        {
            controller = [[MainViewController alloc] initWithPageNumber:i team:[[favoritesArray objectAtIndex:i] teamR]];
            [controllers replaceObjectAtIndex:i withObject:controller];
            [controller release];
        }
        if (nil == controller.view.superview)
        {
            CGRect frame = scrollView.frame;
            frame.origin.x = frame.size.width * i;
            frame.origin.y = 0;
            controller.view.frame = frame;
            [scrollView addSubview:controller.view];
        }
    }
    //********************CRASH******************
    //Ideally, I think, the line below would replace the contents of
    //viewControllers with the new controllers. Here is where I get the 
    //"objc[10801]: FREED(id): message release sent to freed object=0x3f4a490" 
    //error. This line should probably be placed after [self loadData] or something,
    //but it crashes so I put but here to display better. I tried
    //adding self.viewControllers = nil; but I don't think that is 
    //the problem with the error message.
    self.viewControllers = controllers;
}

该reloadDataNow方法从子视图中调用，其中可以添加或删除要在滚动视图上显示的项目。

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1 回答 1

2

（我遇到了同样的问题，我想将UIImageView's 添加到我的 mainView 并像这样更新它们）我只是使用了一个 NSMutable 数组，其中包含要在视图中显示的 ViewControllers，然后根据需要添加或减去它，并且每次从该数组中添加或减去时，然后从 mainView 内部调用一个方法，该方法通过scrollView并从scrollView中删除每个视图，然后将适当的viewController添加到scrollView。希望这可以帮助。

于 2010-03-05T03:43:14.327 回答