ios - 在 Unwind Segue 中清除导航 Controller

Question

我有一个连接两个 View 的 segue。在父 View 中，导航栏是灰色的，而在 subview 中，它是清晰的。展开 segue 时，父 Controller 中的导航栏现在也清晰可见。如何解决这个问题？

父 Controller

  override func viewWillAppear(animated: Bool) {
    self.navigationItem.title = "FEED"
    self.navigationController?.navigationBar.barTintColor = UIColor(white:0.97, alpha:1.0)
    let navBarLineView = UIView(frame: CGRectMake(0,
        CGRectGetHeight((navigationController?.navigationBar.frame)!),
        CGRectGetWidth((self.navigationController?.navigationBar.frame)!),
        1))
    navBarLineView.backgroundColor = UIColor(red:0.91, green:0.91, blue:0.92, alpha:1.0)
    navigationController?.navigationBar.addSubview(navBarLineView)
}

子 Controller

 override func viewWillAppear(animated: Bool) {
    self.navigationItem.title = "Space
    self.navigationController?.navigationBar.barTintColor = UIColor.whiteColor()

    navigationController!.navigationBar.setBackgroundImage(UIImage(), forBarMetrics: UIBarMetrics.Default)
    navigationController!.navigationBar.shadowImage = UIImage()
    navigationController!.navigationBar.translucent = true
}

Answer 1

当我想恢复导航栏的默认样式时，在子 Controller 的 viewWillDisappear 方法中将背景和阴影图像设置为 nil 对我来说效果很好:

override func viewWillDisappear(animated: Bool) {
    navigationController!.navigationBar.setBackgroundImage(nil, forBarMetrics: UIBarMetrics.Default)
    navigationController!.navigationBar.shadowImage = nil
}