Receiver（<viewcontroller：>）没有带标识符'showAlerting''</viewcontroller：>的segue

Question

segue运行但应用程序因上述错误而崩溃。为什么我收到此no segue with identifier消息？我定义了segue标识符。

这是viewDidAppear方法

- (void)viewDidAppear:(BOOL)animated
{
   [self performSegueWithIdentifier:@"showAlerting" sender:self];
}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([[segue identifier] isEqualToString:@"showAlerting"])
    {
        NSLog(@"Logging showAlerting");
    }
}

我收到了这些日志消息

2015-03-28 20:04:33.025 xxxx[3684:741007] Logging showAlerting
2015-03-28 20:04:33.046 xxxx[3684:741007] xxxxxxxx,,
2015-03-28 20:04:33.111 xxxx[3684:741007]  lat: xxx
2015-03-28 20:04:33.112 xxxx[3684:741007]  lon: xxx
2015-03-28 20:04:33.798 xxxx[3684:741007] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Receiver (<ViewController: 0x17d38930>) has no segue with identifier 'showAlerting''
*** First throw call stack:
(0x2c1a15a7 0x39d87c77 0x2f9830df 0xebde7 0x2f6bb37b 0x2f6bb837 0x2f9701bb 0x2fd00e89 0x2f9726ff 0x2f7b5baf 0x2f7b5a4f 0x2f7b5525 0x2f6d9201 0x2f6d9117 0x2f0d363b 0x276187 0x279e9d 0x2c167891 0x2c165fb1 0x2c0b2b51 0x2c0b2963 0x335f11a9 0x2f704c91 0xea5f5 0x3a330aaf)
libc++abi.dylib: terminating with uncaught exception of type NSException

Answer 1

问题是你在故事板中有两个同一个类的实例;一个与segue，一个没有。被调查的控制器需要与你所分离的控制器不同。

Answer 2

当您尝试访问其segue时，您的视图控制器未完全加载。因此，调用super并完成加载过程，然后调用prepareForSegue。

  -(void)viewDidAppear:(BOOL)animated{
      [super viewDidAppear:animated];
      [self performSegueWithIdentifier:@"showAlerting" sender:self];
    }