当我使用prepareForSegue将值传递给目标控制器时，存在一些问题 [英] When I use prepareForSegue to pass value to the aim controller, there are some problems

问题描述

首先，我使用storyboard创建两个uiviewcontroller： firstviewcontroller 和 secondviewcontroller 。并使用xcode将 uinavigationcontroller 嵌入 secondviewcontroller （编辑器 - >嵌入 - >导航控制器）。然后，我还想使用segue将值从第一个传递到第二个。有代码：

Firstly, I use storyboard to create two uiviewcontroller: firstviewcontroller and secondviewcontroller. And using xcode to embed a uinavigationcontroller into secondviewcontroller(editor --> embed in --> navigation controller). Then, I also want to use segue to pass value from first to second. there is the code:

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if([segue.identifier isEqualToString:@"passValue"])
    {
        secondViewController *saveViewController = [segue destinationViewController];
        [saveViewController setValue:data forKey:@"data"];
    }
}

但是报告错误，日志是：
由于未捕获的异常'NSUnknownKeyException'而终止应用程序，原因：'[setValue：forUndefinedKey：]：此类不是密钥数据的密钥值编码兼容。'

But there will report error, the log is: Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[ setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key data.'

但是，当我删除导航控制器时，我使用Xcode插入它并按代码定义导航栏，此问题将消失。我想原因是真正的destinationViewController是 navigationcontroller 而不是 secondviewcontroller 。因此，如果我想保留Xcode嵌入的导航控制器，如何解决这个问题？

However, when I delete the navigation controller that I use Xcode to insert it and define the navigation bar by code, this problem will disappear. I guess the reason is the real destinationViewController is navigationcontroller instead of secondviewcontroller. So if I want to reserve the navigation controller that is embedded by Xcode, how can fix this problem?

推荐答案

你是对的， destinationViewController 将是 UINavigationController ，其中嵌入了 secondViewController 。也许试试：

You're right, destinationViewController will be a UINavigationController you have secondViewController embeded in. Maybe try that:

secondViewController *saveViewController = [[segue destinationViewController] topViewController];

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