这里有一个非常简单的解决方案:

self.navigationController.navigationBar.clipsToBounds = YES;

酒吧风格的黑色适合我。

[[UINavigationBar appearance] setBarStyle:UIBarStyleBlack];

我拥有的所有属性(以防万一):

    [[UINavigationBar appearance] setBarTintColor:color];
    [[UINavigationBar appearance] setTranslucent:NO];
    [[UINavigationBar appearance] setShadowImage:[UIImage new]];
    [[UINavigationBar appearance] setBarStyle:UIBarStyleBlack];

两条线的解决方案对我来说很有效。尝试在ViewDidLoad方法中添加这个:

navigationController?.navigationBar.setValue(true, forKey: "hidesShadow")
self.extendedLayoutIncludesOpaqueBars = true

也可以从故事板中隐藏(适用于Xcode 10.1)

通过添加运行时属性:hidshadow - Boolean - True

编写自己的初始化式:D

import Foundation
import UIKit

extension UINavigationController {
    convenience init(rootViewController : UIViewController, hidesShadow : Bool) {
        self.init(rootViewController : rootViewController)
        self.navigationBar.setValue(hidesShadow, forKey: "hidesShadow")
        if hidesShadow {
            self.extendedLayoutIncludesOpaqueBars = true
            self.navigationBar.isTranslucent = false 
        }
    }
}

你应该在UISearchBar的底部添加一个视图

let rect = searchController.searchBar.frame;
let lineView : UIView = UIView.init(frame: CGRect.init(x: 0, y: rect.size.height-1, width: rect.size.width, height: 1))
lineView.backgroundColor = UIColor.init(hexString: "8CC73E")
searchController.searchBar.addSubview(lineView)