在AppDelegate中，这已经全局地改变了导航栏的格式，并删除了底线/边界(这对大多数人来说是一个问题区域)，给你我认为你和其他人正在寻找的东西:

 func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

    UINavigationBar.appearance().setBackgroundImage(UIImage(), forBarPosition: UIBarPosition.Any, barMetrics: UIBarMetrics.Default)
    UINavigationBar.appearance().shadowImage = UIImage()
    UINavigationBar.appearance().tintColor = UIColor.whiteColor()
    UINavigationBar.appearance().barTintColor = Style.SELECTED_COLOR
    UINavigationBar.appearance().translucent = false
    UINavigationBar.appearance().clipsToBounds = false
    UINavigationBar.appearance().backgroundColor = Style.SELECTED_COLOR
    UINavigationBar.appearance().titleTextAttributes = [NSFontAttributeName : (UIFont(name: "FONT NAME", size: 18))!, NSForegroundColorAttributeName: UIColor.whiteColor()] }

然后你可以设置一个Constants.swift文件，其中包含一个带有颜色和字体等的样式结构。然后你可以添加一个tableView/pickerView到任何ViewController，并使用“availableThemes”数组允许用户改变themeColor。

关于这一点的美妙之处在于，你可以在整个应用程序中为每种颜色使用一个引用，它会根据用户选择的“主题”进行更新，如果没有一个，它默认为theme1():

import Foundation
import UIKit

struct Style {


static let availableThemes = ["Theme 1","Theme 2","Theme 3"]

static func loadTheme(){
    let defaults = NSUserDefaults.standardUserDefaults()
    if let name = defaults.stringForKey("Theme"){
        // Select the Theme
        if name == availableThemes[0]   { theme1()  }
        if name == availableThemes[1]   { theme2()  }
        if name == availableThemes[2]   { theme3()  }
    }else{
        defaults.setObject(availableThemes[0], forKey: "Theme")
        theme1()
    }
}

 // Colors specific to theme - can include multiple colours here for each one
static func theme1(){
   static var SELECTED_COLOR = UIColor(red:70/255, green: 38/255, blue: 92/255, alpha: 1) }

static func theme2(){
    static var SELECTED_COLOR = UIColor(red:255/255, green: 255/255, blue: 255/255, alpha: 1) }

static func theme3(){
    static var SELECTED_COLOR = UIColor(red:90/255, green: 50/255, blue: 120/255, alpha: 1) } ...

这里有一些非常基本的外观定制，你可以应用于整个应用程序:

UINavigationBar.appearance().backgroundColor = UIColor.greenColor()
UIBarButtonItem.appearance().tintColor = UIColor.magentaColor()
//Since iOS 7.0 UITextAttributeTextColor was replaced by NSForegroundColorAttributeName
UINavigationBar.appearance().titleTextAttributes = [UITextAttributeTextColor: UIColor.blueColor()]
UITabBar.appearance().backgroundColor = UIColor.yellowColor();

斯威夫特5.4.2:

UINavigationBar.appearance().backgroundColor = .green // backgorund color with gradient
// or
UINavigationBar.appearance().barTintColor = .green  // solid color
    
UIBarButtonItem.appearance().tintColor = .magenta
UINavigationBar.appearance().titleTextAttributes = [NSAttributedString.Key.foregroundColor : UIColor.blue]
UITabBar.appearance().barTintColor = .yellow

更多关于UIAppearance API在Swift你可以阅读这里。

appearance()函数并不总是适用于我。所以我更喜欢创建一个NC对象并改变它的属性。

var navBarColor = navigationController!.navigationBar
navBarColor.barTintColor =
    UIColor(red:  255/255.0, green: 0/255.0, blue: 0/255.0, alpha: 100.0/100.0)
navBarColor.titleTextAttributes =
    [NSForegroundColorAttributeName: UIColor.whiteColor()]

此外，如果你想添加一个图像而不仅仅是文本，这也是可行的

var imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: 70, height: 70))
imageView.contentMode = .ScaleAspectFit

var image = UIImage(named: "logo")
imageView.image = image
navigationItem.titleView = imageView

在AppDelegate中试试这个:

//MARK:- ~~~~~~~~~~setupApplicationUIAppearance Method
func setupApplicationUIAppearance() {

    UIApplication.shared.statusBarView?.backgroundColor = UIColor.clear

    var preferredStatusBarStyle: UIStatusBarStyle {
        return .lightContent
    }

    UINavigationBar.appearance().tintColor = #colorLiteral(red: 1, green: 1, blue: 1, alpha: 1)
    UINavigationBar.appearance().barTintColor =  UIColor.white
    UINavigationBar.appearance().isTranslucent = false

    let attributes: [NSAttributedString.Key: AnyObject]

    if DeviceType.IS_IPAD{
        attributes = [
            NSAttributedString.Key.foregroundColor: UIColor.white,
            NSAttributedString.Key.font: UIFont(name: "HelveticaNeue", size: 30)
            ] as [NSAttributedString.Key : AnyObject]
    }else{
        attributes = [
            NSAttributedString.Key.foregroundColor: UIColor.white
        ]
    }
    UINavigationBar.appearance().titleTextAttributes = attributes
}

iOS 13

func setupNavigationBar() {
    //        if #available(iOS 13, *) {
    //            let window = UIApplication.shared.windows.filter {$0.isKeyWindow}.first
    //            let statusBar = UIView(frame: window?.windowScene?.statusBarManager?.statusBarFrame ?? CGRect.zero)
    //            statusBar.backgroundColor = #colorLiteral(red: 0.2784313725, green: 0.4549019608, blue: 0.5921568627, alpha: 1) //UIColor.init(hexString: "#002856")
    //            //statusBar.tintColor = UIColor.init(hexString: "#002856")
    //            window?.addSubview(statusBar)
    //            UINavigationBar.appearance().tintColor = #colorLiteral(red: 1, green: 1, blue: 1, alpha: 1)
    //            UINavigationBar.appearance().barTintColor = #colorLiteral(red: 1, green: 1, blue: 1, alpha: 1)
    //            UINavigationBar.appearance().isTranslucent = false
    //            UINavigationBar.appearance().backgroundColor = #colorLiteral(red: 0.2784313725, green: 0.4549019608, blue: 0.5921568627, alpha: 1)
    //            UINavigationBar.appearance().titleTextAttributes = [NSAttributedString.Key.foregroundColor : UIColor.white]
    //        }
    //        else
    //        {
    UIApplication.shared.statusBarView?.backgroundColor = #colorLiteral(red: 0.2784313725, green: 0.4549019608, blue: 0.5921568627, alpha: 1)
    UINavigationBar.appearance().tintColor = #colorLiteral(red: 1, green: 1, blue: 1, alpha: 1)
    UINavigationBar.appearance().barTintColor = #colorLiteral(red: 1, green: 1, blue: 1, alpha: 1)
    UINavigationBar.appearance().isTranslucent = false
    UINavigationBar.appearance().backgroundColor = #colorLiteral(red: 0.2784313725, green: 0.4549019608, blue: 0.5921568627, alpha: 1)
    UINavigationBar.appearance().titleTextAttributes = [NSAttributedString.Key.foregroundColor : UIColor.white]
    //        }
}

扩展

extension UIApplication {

var statusBarView: UIView? {
    if responds(to: Selector(("statusBar"))) {
        return value(forKey: "statusBar") as? UIView
    }
    return nil
}}

确保将按钮状态设置为.normal

extension UINavigationBar {

    func makeContent(color: UIColor) {
        let attributes: [NSAttributedString.Key: Any]? = [.foregroundColor: color]

        self.titleTextAttributes = attributes
        self.topItem?.leftBarButtonItem?.setTitleTextAttributes(attributes, for: .normal)
        self.topItem?.rightBarButtonItem?.setTitleTextAttributes(attributes, for: .normal)
    }
}

ps iOS 12, Xcode 10.1

在iOS 15中，UIKit扩展了scrollEdgeAppearance的使用，默认情况下它会生成透明的背景，用于所有导航栏。 设置scrollEdgeAppearance如下代码。

if #available(iOS 15, *) {
        let appearance = UINavigationBarAppearance()
        appearance.configureWithOpaqueBackground()
        appearance.backgroundColor = < your tint color >
        navigationController?.navigationBar.standardAppearance = appearance;
        navigationController?.navigationBar.scrollEdgeAppearance = navigationController?.navigationBar.standardAppearance
    }