如果你的viewController在UINavigationController下面。

子类UINavigationController并添加

override var preferredStatusBarStyle: UIStatusBarStyle {
    return topViewController?.preferredStatusBarStyle ?? .default
}

ViewController的preferredStatusBarStyle将被调用。

如果有人正在使用一个导航控制器，并希望他们所有的导航控制器都有黑色风格，你可以在Swift 3中写一个扩展到UINavigationController，它将应用于所有的导航控制器(而不是一次分配给一个控制器)。

extension UINavigationController {

    override open func viewDidLoad() {
        super.viewDidLoad()

        self.navigationBar.barStyle = UIBarStyle.black
    }

}

Swift 4.2及以上版本

正如所选答案中提到的，根本原因是检查您的窗口根视图控制器对象。

流结构的可能情况

Custom UIViewController object is window root view controller Your window root view controller is a UIViewController object and it further adds or removes navigation controller or tabController based on your application flow. This kind of flow is usually used if your app has pre login flow on navigation stack without tabs and post login flow with tabs and possibly every tab further holds navigation controller. TabBarController object is window root view controller This is the flow where window root view controller is tabBarController possibly every tab further holds navigation controller. NavigationController object is window root view controller This is the flow where window root view controller is navigationController. I am not sure if there is any possibility to add tab bar controller or new navigation controller in an existing navigation controller. But if there is such case, we need to pass the status bar style control to the next container. So, I added the same check in UINavigationController extension to find childForStatusBarStyle

使用以下扩展，它处理所有上述场景-

extension UITabBarController {
    open override var childForStatusBarStyle: UIViewController? {
        return selectedViewController?.childForStatusBarStyle ?? selectedViewController
    }
}

extension UINavigationController {
    open override var childForStatusBarStyle: UIViewController? {
        return topViewController?.childForStatusBarStyle ?? topViewController
    }
}

extension AppRootViewController {
    open override var preferredStatusBarStyle: UIStatusBarStyle {
        return children.first { $0.childForStatusBarStyle != nil }?.childForStatusBarStyle?.preferredStatusBarStyle ?? .default
    }
}

在info中你不需要UIViewControllerBasedStatusBarAppearance键。Plist默认为true

对于更复杂的流程，需要考虑的要点

In case you present new flow modally, it detaches from the existing status bar style flow. So, suppose you are presenting a NewFlowUIViewController and then add new navigation or tabBar controller to NewFlowUIViewController, then add extension of NewFlowUIViewController as well to manage further view controller's status bar style. In case you set modalPresentationStyle other than fullScreen while presenting modally, you must set modalPresentationCapturesStatusBarAppearance to true so that presented view controller must receive status bar appearance control.

Swift 3 iOS 10解决方案:

override var preferredStatusBarStyle: UIStatusBarStyle {
    return .lightContent
 }

大多数答案都不包括UINavigationController的childViewControllerForStatusBarStyle方法的良好实现。根据我的经验，你应该处理这样的情况，当透明的视图控制器在导航控制器。在这些情况下，你应该把控制传递给你的模态控制器(visibleViewController)，但不要在它消失的时候。

override var childViewControllerForStatusBarStyle: UIViewController? {
  var childViewController = visibleViewController
  if let controller = childViewController, controller.isBeingDismissed {
    childViewController = topViewController
  }
  return childViewController?.childViewControllerForStatusBarStyle ?? childViewController
}

我的应用程序使用了所有三个:UINavigationController, UISplitViewController, UITabBarController，因此这些似乎都接管了对状态栏的控制，并将导致preferedStatusBarStyle不为他们的孩子被调用。要覆盖此行为，您可以创建一个扩展，就像前面提到的其他答案一样。这是一个扩展，这三个，在Swift 4。希望苹果对这类事情能更清楚些。

extension UINavigationController {
    open override var childViewControllerForStatusBarStyle: UIViewController? {
        return self.topViewController
    }

    open override var childViewControllerForStatusBarHidden: UIViewController? {
        return self.topViewController
    }
}

extension UITabBarController {
    open override var childViewControllerForStatusBarStyle: UIViewController? {
        return self.childViewControllers.first
    }

    open override var childViewControllerForStatusBarHidden: UIViewController? {
        return self.childViewControllers.first
    }
}

extension UISplitViewController {
    open override var childViewControllerForStatusBarStyle: UIViewController? {
        return self.childViewControllers.first
    }

    open override var childViewControllerForStatusBarHidden: UIViewController? {
        return self.childViewControllers.first
    }
}

编辑:针对Swift 4.2 API更改的更新

extension UINavigationController {
    open override var childForStatusBarStyle: UIViewController? {
        return self.topViewController
    }

    open override var childForStatusBarHidden: UIViewController? {
        return self.topViewController
    }
}

extension UITabBarController {
    open override var childForStatusBarStyle: UIViewController? {
        return self.children.first
    }

    open override var childForStatusBarHidden: UIViewController? {
        return self.children.first
    }
}

extension UISplitViewController {
    open override var childForStatusBarStyle: UIViewController? {
        return self.children.first
    }

    open override var childForStatusBarHidden: UIViewController? {
        return self.children.first
    }
}