在按照上面大家说的去做之后，也就是:

navigationController?.navigationBar.setBackgroundImage(UIImage(), forBarMetrics: .default)
navigationController?.navigationBar.shadowImage = UIImage()
navigationController!.navigationBar.isTranslucent = true

．.． 我的导航栏还是白色的。所以我加了这一行:

navigationController?.navigationBar.backgroundColor = .clear

．.． 果不其然!这似乎奏效了。

在iOS5中，你可以这样做，使导航栏透明:

nav.navigationBar.translucent = YES; // Setting this slides the view up, underneath the nav bar (otherwise it'll appear black)
const float colorMask[6] = {222, 255, 222, 255, 222, 255};
UIImage *img = [[UIImage alloc] init];
UIImage *maskedImage = [UIImage imageWithCGImage: CGImageCreateWithMaskingColors(img.CGImage, colorMask)];

[nav.navigationBar setBackgroundImage:maskedImage forBarMetrics:UIBarMetricsDefault]; 
[img release];

下面的代码扩展了为这个线程选择的顶部答案，以消除底部边框并设置文本颜色:

The last two coded lines of this code set transparency. I borrowed that code from this thread and it worked perfectly! The "clipsToBounds" property was code I found which got rid of the bottom border line with OR without transparency set (so if you decide to go with a solid white/black/etc. background instead, there will still be no border line). The "tintColor" line (2nd coded line) set my back button to a light grey I kept barTintColor as a backup. I don't know why transparency would not work, but if it doesn't, I want my bg white as I used to have it let navigationBarAppearace = UINavigationBar.appearance() navigationBarAppearace.tintColor = UIColor.lightGray navigationBarAppearace.barTintColor = UIColor.white navigationBarAppearace.clipsToBounds = true navigationBarAppearace.isTranslucent = true navigationBarAppearace.setBackgroundImage(UIImage(), for: .default) navigationBarAppearace.shadowImage = UIImage()

检查RRViewControllerExtension，它专门用于uinnavigation栏外观管理。

在你的项目中使用RRViewControllerExtension，你只需要覆盖

-(BOOL)prefersNavigationBarTransparent;

在你的视图控制器中。

解决方案- Swift 5 - iOS 13+

根据文档，在你的UIViewController子类中:

override func viewDidLoad()
{
    super.viewDidLoad()
    
    let appearance = UINavigationBarAppearance()
    appearance.configureWithTransparentBackground()
    //appearance.backgroundColor = UIColor.clear
    
    navigationItem.compactAppearance = appearance
    navigationItem.scrollEdgeAppearance = appearance
    navigationItem.standardAppearance = appearance
    
    //...
}

只是为了澄清，这使得UINavigationBar完全透明。栏按钮项仍然可见，并正常工作。

什么不起作用

override func viewDidLoad()
{
    super.viewDidLoad()
    
    navigationController?.navigationBar.isTranslucent = true
    navigationController?.navigationBar.isOpaque = false

    //...
}

这让我意识到我其实不知道透明RIP和半透明RIP之间的区别。

参考文献

https://developer.apple.com/documentation/uikit/uinavigationcontroller/customizing_your_app_s_navigation_bar

https://www.lexico.com/en/definition/transparent

https://www.lexico.com/en/definition/translucent

更新08/10/2021

在以我提供的方式设置外观后，更改navigationItem栏按钮将重置外观，您必须再次执行此操作。

另一种方式，为我工作是子类UINavigationBar和留下drawRect方法空!!

@IBDesignable class MONavigationBar: UINavigationBar {


// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func drawRect(rect: CGRect) {
    // Drawing code
}}