如何在一个视图控制器中使UINavigationController透明？

Question

我想让NavigationBar在一个ViewController中变得透明。但是，在单个ViewController中更改NavigationBar时，整个navigationController就会变得透明，几秒钟后crashes.Here就是我的代码块了：

override func viewWillAppear(animated: Bool) {
        self.navigationController!.navigationBar.setBackgroundImage(UIImage(), forBarMetrics: UIBarMetrics.Default)
        self.navigationController?.navigationBar.shadowImage = UIImage()
        self.navigationController?.navigationBar.translucent = true
        self.navigationController!.view.backgroundColor = UIColor.clearColor()
    }



override func viewDidDisappear(animated: Bool) {
        self.navigationController!.navigationBar.setBackgroundImage(nil, forBarMetrics: UIBarMetrics.Default)
        self.navigationController?.navigationBar.shadowImage = nil
        self.navigationController?.navigationBar.translucent = true

    }

它崩溃成一条线

self.navigationController!.navigationBar.setBackgroundImage(nil, forBarMetrics: UIBarMetrics.Default)

Answer 1

我们可以像这样实现这个需求：

在哪个UIViewController中我们想要清除NavigationBar颜色应该在UIViewController中清楚我们需要用viewDidLoad，viewWillAppear和viewWillDisappear方法编写这些代码

在viewDidLoad方法中，为了获得更好的显示效果，我们需要编写代码片段，如果我们没有编写put代码片段，那么在显示will视图之后，navigation bar的颜色将发生变化。

override func viewDidLoad() {
    super.viewDidLoad()
    self.navigationController?.navigationBar.setBackgroundImage(UIImage(), for: .default)
    self.navigationController?.navigationBar.shadowImage = UIImage()
    self.navigationController?.navigationBar.isTranslucent = true
}


override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    self.navigationController?.navigationBar.setBackgroundImage(UIImage(), for: .default)
    self.navigationController?.navigationBar.shadowImage = UIImage()
    self.navigationController?.navigationBar.isTranslucent = true
    self.navigationController?.navigationBar.barTintColor = UIColor.clear
    self.navigationController?.navigationBar.backgroundColor = UIColor.clear
}

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)

    self.navigationController?.navigationBar.setBackgroundImage(nil, for: .default)
    self.navigationController?.navigationBar.shadowImage = nil
    self.navigationController?.navigationBar.isTranslucent = true
}

当我们移动到同一个UINavigationController上的其他屏幕(按下另一个UIViewController)时，我们需要设置barTintColor，否则它将显示为黑色。

Answer 2

尝试使用给定的代码在swift中使导航栏透明:-

    self.navigationController!.navigationBar.setBackgroundImage(UIImage(), forBarMetrics: UIBarMetrics.Default)
    self.navigationController?.navigationBar.shadowImage = UIImage()
    self.navigationController?.navigationBar.translucent = true
    self.navigationController!.view.backgroundColor = UIColor.clearColor()
    self.navigationController?.navigationBar.backgroundColor = UIColor.clearColor()

希望这段代码能帮助你..谢谢

Answer 3

Swift 4

self.navigationController?.navigationBar.setBackgroundImage(UIImage(), for: UIBarMetrics.default)
self.navigationController?.navigationBar.shadowImage = UIImage()
self.navigationController?.navigationBar.isTranslucent = true
self.navigationController?.view.backgroundColor = UIColor.clear
self.navigationController?.navigationBar.backgroundColor = UIColor.clear