ios - 无法导航到 iOS 9 中的其他屏幕

Question

我正在从第二个屏幕导航到第三个屏幕，但显示错误应用程序试图在目标上推送一个零 View Controller 。这是我用来导航的以下代码，

 if (appDelegate.thirdViewController == nil) {
    ThirdViewController *sThirdViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"ThirdViewController"];
    [appDelegate setThirdViewController:sThirdViewController];
}

[self.navigationController pushViewController:appDelegate.thirdViewController animated:YES];

Answer 1

似乎 AppDelegate 没有引用，

你写了 appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];

检查一次..