Question

Apple在他们的iOS开发网站上展示了如何使用具有不同详细视图（see MultipleDetailViews Example）的splitview的示例。在RootViewController eery时间内选择单元格，初始化一个新的DetailViewController：

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

/*
 Create and configure a new detail view controller appropriate for the selection.
 */
NSUInteger row = indexPath.row;

UIViewController <SubstitutableDetailViewController> *detailViewController = nil;

if (row == 0) {
    FirstDetailViewController *newDetailViewController = [[FirstDetailViewController alloc] initWithNibName:@"FirstDetailView" bundle:nil];
    detailViewController = newDetailViewController;
}

if (row == 1) {
    SecondDetailViewController *newDetailViewController = [[SecondDetailViewController alloc] initWithNibName:@"SecondDetailView" bundle:nil];
    detailViewController = newDetailViewController;
}

// Update the split view controller's view controllers array.
NSArray *viewControllers = [[NSArray alloc] initWithObjects:self.navigationController, detailViewController, nil];
splitViewController.viewControllers = viewControllers;
[viewControllers release];

// Dismiss the popover if it's present.
if (popoverController != nil) {
    [popoverController dismissPopoverAnimated:YES];
}

// Configure the new view controller's popover button (after the view has been displayed and its toolbar/navigation bar has been created).
if (rootPopoverButtonItem != nil) {
    [detailViewController showRootPopoverButtonItem:self.rootPopoverButtonItem];
}

[detailViewController release];
}

现在我的想法是不是每次都初始化viewcontrollers，只是初始化viewDidLoad（以及标题）中的控制器，并在选择单元格时传递它们的引用：

rootviewcontroller中viewDidLoad的一部分：

firstDetailViewController = [[FirstDetailViewController alloc] initWithNibName:@"FirstDetailView" bundle:nil];
secondDetailViewController = [[FirstDetailViewController alloc] initWithNibName:@"FirstDetailView" bundle:nil];

现在tableView didselectrow方法如下所示：

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

/*
 Create and configure a new detail view controller appropriate for the selection.
 */
NSUInteger row = indexPath.row;

UIViewController <SubstitutableDetailViewController> *detailViewController = nil;

if (row == 0) {
    detailViewController = firstDetailViewController;
}

if (row == 1) {
    detailViewController = secondDetailViewController;
}

// Update the split view controller's view controllers array.
NSArray *viewControllers = [[NSArray alloc] initWithObjects:self.navigationController, detailViewController, nil];
splitViewController.viewControllers = viewControllers;
[viewControllers release];

// Dismiss the popover if it's present.
if (popoverController != nil) {
    [popoverController dismissPopoverAnimated:YES];
}

// Configure the new view controller's popover button (after the view has been displayed and its toolbar/navigation bar has been created).
if (rootPopoverButtonItem != nil) {
    [detailViewController showRootPopoverButtonItem:self.rootPopoverButtonItem];
}

//[detailViewController release];
}

在横向模式下，一切正常，但在纵向模式下，从第一个视图控制器切换到第二个，然后转到第一个然后想要切换到第二个时，会出现错误。发生以下消息：由于未捕获的异常'NSInvalidArgumentException'终止应用程序，原因：'无法从没有窗口的视图中显示弹出窗口。'

从昨天晚上开始，我试图解决这个问题，但我找不到解决办法。有人有想法吗？

干杯，多米尼克

Answer 1

我遇到了类似的问题，但我发现这个post证明了在设置splitView的视图控制器之前必须从之前的detailView中删除leftBarButtonItem的想法。这段代码为我解决了这个问题。

这是TPoschel编写的代码。

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

// Retrieve the new detail view controller
UIViewController *detailViewController = [[self.allData objectAtIndex:indexPath.section] objectAtIndex:indexPath.row];

// Add the detail view controller to a navigation controller and set the bar style
UINavigationController *detailNavigationController = [[UINavigationController alloc] initWithRootViewController:detailViewController];
detailNavigationController.navigationBar.barStyle = [[NSUserDefaults standardUserDefaults] integerForKey:@"UIBarStyle"];

// Retrieve previous detail view controller and remove the leftBarButtonItem
UINavigationController *previousDetailNavigationController = [splitViewController.viewControllers objectAtIndex:1];
UIViewController *previousDetailViewController = [[previousDetailNavigationController viewControllers] lastObject];
previousDetailViewController.navigationItem.leftBarButtonItem = nil;

// Update the split view controller's view controllers array.
NSArray *viewControllers = [[NSArray alloc] initWithObjects:self.navigationController, detailNavigationController, nil];
splitViewController.viewControllers = viewControllers;

[detailNavigationController release];
[viewControllers release];

// Dismiss the popover if it's present.
if (popoverController != nil) {
    [popoverController dismissPopoverAnimated:YES];
}

// This sets the left bar to nil when in landscape and equal to "Menu" when in portrait.
// We need to remove rootPopoverButtonItem from the previous viewController...
detailViewController.navigationItem.leftBarButtonItem = rootPopoverButtonItem;

}

在Apples MultipleDetailViews示例中加载已初始化的DetailViewControllers

1 个答案: