xcode 应用程序试图在目标上呈现一个 nil 模态视图控制器
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Application tried to present a nil modal view controller on target
提问by Sinead
I have a simple single view app with two storyboards with different layouts for portrait and landscape. The landscape layout is completely different which is why I am using a second storyboard.
我有一个简单的单视图应用程序，其中包含两个故事板，纵向和横向布局各不相同。横向布局完全不同，这就是我使用第二个故事板的原因。
When I switch to landscape the view doesn't change and I get the
当我切换到横向时，视图不会改变，我得到了
"Application tried to present a nil modal view controller on target"
“应用程序试图在目标上呈现一个 nil 模态视图控制器”
` error in the debugger. I have checked that the landscape storyboard is referencing to the CalculatorViewController class.
` 调试器中的错误。我检查了风景故事板是否引用了 CalculatorViewController 类。
This is the line of code which generates the error:
这是生成错误的代码行：
[self presentViewController:landscapeViewController animated:YES completion:nil];
Here is the whole method from CalculatorViewController.m:
这是来自 CalculatorViewController.m 的整个方法：
- (void)orientationChanged:(NSNotification *)notification
{
UIDeviceOrientation deviceOrientation = [UIDevice currentDevice].orientation;
if (UIDeviceOrientationIsLandscape(deviceOrientation) &&
!isShowingLandscapeView)
{
// code here to show landscape storyboard
UIStoryboard *landscapeStoryboard = [UIStoryboard storyboardWithName:@"LandscapeStoryboard" bundle:nil];
CalculatorViewControllerLandscape *landscapeViewController = [landscapeStoryboard instantiateInitialViewController];
[self presentViewController:landscapeViewController animated:YES completion:nil];
isShowingLandscapeView = YES;
}
else if (UIDeviceOrientationIsPortrait(deviceOrientation) &&
isShowingLandscapeView)
{
[self dismissViewControllerAnimated:YES completion:nil];
isShowingLandscapeView = NO;
}
}
The Initial View Controller is called CalculatorViewController. The View Controller for the landscape layout is called CalculatorViewControllerLandscape.
初始视图控制器称为 CalculatorViewController。横向布局的视图控制器称为 CalculatorViewControllerLandscape。
This is my first app so I really appreciate any help. I have tried to find a solution in similar questions posted without success.
这是我的第一个应用程序，所以我非常感谢任何帮助。我试图在没有成功发布的类似问题中找到解决方案。
回答by Gabriele Petronella
It means that landscapeViewControlleris nil.
这意味着landscapeViewController是nil。
This can be cause by either:
这可能是由以下任一原因引起的：
landscapeStoryboardbeingnil(most likely because a storyboard namedLandscapeStoryboardcannot be found)- no initial view controller being indicated in the storyboard.
landscapeStoryboard正在nil（很可能是因为LandscapeStoryboard找不到命名的故事板）- 故事板中没有指示初始视图控制器。
回答by JFS
You need to make sure that the identifier for the storyboard landscape-view is set to "LandscapeStoryboard". Select the storyboard and check the identifier.
您需要确保故事板横向视图的标识符设置为“LandscapeStoryboard”。选择故事板并检查标识符。
