导航栏下方会出现黑条

问题描述：

有几个类似的问题没有得到答案，但含糊地描述。我已将问题缩减为非常薄的应用程序，并添加了详细的屏幕截图。我非常感谢这个解决方案！

There are several similar questions which got no answers but were describe vaguely. I have reduced the problem into a very thin application, and added detailed screenshots. I would highly appreciate a solution for this!

唯一涉及的代码是一行添加到根VC的viewDidLoad 。这一行的目的是使导航控制器不透明：

The only involved code is one line added to viewDidLoad of the root VC. The purpose of this line is to make the navigation controller opaque:

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.navigationController.navigationBar.translucent = NO;
}

此问题的一个重要信息是'Title1'有一个提示在其导航项中，而'Title2'没有提示。

A critical information for this question is that 'Title1' has a prompt in its navigation item, while 'Title2' has not prompt.

我有一个带有一个导航控制器的故事板，一个root VC称为Title1，带有一个segue按钮，该按钮带到第二个名为Title2的VC

I have a storyboard with one navigation controller, one root VC called "Title1", with a segue button which takes to a second VC called "Title2"

按此处按钮时：

我收到了这个奇怪的屏幕：

I'm getting this strange screen:

按下后（Title1），它会得到更糟糕的是（即：标题1的原始标签被推高，现在不再被看见!!!）：

When pressing back (Title1), it gets worse (i.e.: the original label of Title1 was pushed up and now not being seen anymore!!!):

任何人都可以吗？

答

迟到的答案我偶然发现了这个今天的问题，发现你的问题，但它还没有接受答案。

Late answer but I stumbled across this problem today and found your question and it doesn't have an accepted answer yet.

我从故事板中的提示viewController转到非提示的viewController时出现此错误。

I got this error while going from a prompted viewController to a non prompted viewController in storyboard.

我和你一样得到了这个黑条。

I got that black bar just like you.

并修复：

// In prompted vc
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    UIView.setAnimationsEnabled(false)
    self.navigationItem.prompt = nil
    UIView.setAnimationsEnabled(true)
}

这将在切换viewcontroller之前立即删除提示。

This will remove the prompt instantly before switching viewcontroller.

func prompt() -> String? {
    return nil
}

override func viewWillAppear(animated: Bool) {
    let action = { self.navigationItem.prompt = self.prompt() }

    if self.navigationController?.viewControllers.count <= 1 {
        UIView.performWithoutAnimation(action)
    }
    else {
        action()
    }
}

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {        
    UIView.performWithoutAnimation {
        self.navigationItem.prompt = (segue.destinationViewController as? ViewController)?.prompt()
    }
}

导航栏下方会出现黑条

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