UISplitViewController：如何呈现弹出框？

Question

我有一个UISplitViewController，它是一个UISplitViewControllerDelegate，具有以下委托方法：

splitViewController:willHideViewController:withBarButtonItem:forPopoverController:

当 iPad 以纵向启动时，我希望 SplitView 中的 Popover 可见。我该怎么做？

我试过以下代码：

- (void)splitViewController:(UISplitViewController *)svc
     willHideViewController:(UIViewController *)aViewController
          withBarButtonItem:(UIBarButtonItem *)barButtonItem
       forPopoverController:(UIPopoverController *)pc
{
    //setting the barButtonItem in the toolbar in the detail view.

    [pc presentPopoverFromBarButtonItem:barButtonItem permittedArrowDirections:UIPopoverArrowDirectionAny animated:NO];
}

但是上面的代码给了我以下错误：

由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因：“-[UIPopoverController presentPopoverFromRect:inView:permittedArrowDirections:animated:]：无法从没有窗口的视图中呈现弹出框。”

Answer 1

只有一个问题，调用 presentPopover 方法的地方不对，splitViewController:*WillHide*ViewController....... 所以，barButtonItem 存在但屏幕上不存在。我使用了下一个代码，它对我有用。 要处理所有情况，您需要使用 2 种方法。

- (void)viewDidAppear:(BOOL)animated
{
    if ([[UIDevice currentDevice] orientation] == UIDeviceOrientationPortrait || [[UIDevice currentDevice] orientation] == UIDeviceOrientationPortraitUpsideDown) {
        if (self.view.window != nil) {
            [_masterPopoverController presentPopoverFromRect:CGRectMake(0, 0, 1, 1) inView:self.view permittedArrowDirections:UIPopoverArrowDirectionUp animated:NO];
        }
    }
    [super viewDidAppear:animated];
}

和

-(void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation
{
    if (fromInterfaceOrientation == UIDeviceOrientationLandscapeLeft || fromInterfaceOrientation == UIDeviceOrientationLandscapeRight) {
        if (self.view.window != nil) {
            [_masterPopoverController presentPopoverFromRect:CGRectMake(0, 0, 1, 1) inView:self.view permittedArrowDirections:UIPopoverArrowDirectionUp animated:NO];
        }
    }
}