简单的解决方案- Swift 5

Create an extension: extension UIImage { class func hideNavBarLine(color: UIColor) -> UIImage? { let rect = CGRect(x: 0, y: 0, width: 1, height: 1) UIGraphicsBeginImageContext(rect.size) let context = UIGraphicsGetCurrentContext() context?.setFillColor(color.cgColor) context?.fill(rect) let navBarLine = UIGraphicsGetImageFromCurrentImageContext() UIGraphicsEndImageContext() return navBarLine } } Add this to viewDidLoad(): self.navigationController?.navigationBar.shadowImage = UIImage.hideNavBarLine(color: UIColor.clear)

试试这个:

[[UINavigationBar appearance] setBackgroundImage: [UIImage new]  
                                   forBarMetrics: UIBarMetricsDefault];

[UINavigationBar appearance].shadowImage = [UIImage new];

下图有解释(iOS7导航栏):

检查这个SO问题: iOS7 -改变UINavigationBar的边框颜色

不使用navigationController?. navigationbar是非常重要的。setValue(true, forKey: " hidshadow ")因为在任何时候，苹果都可以删除" hidshadow "键路径。如果他们这样做，任何使用这个调用的应用程序都会崩溃。因为你没有访问类的直接API，所以这个调用会被App Store拒绝。

从iOS 13开始，为了确保效率，你可以做以下事情:

navigationBar.standardAppearance.shadowColor = nil

我使用UINavigationBar扩展，使我能够隐藏/显示使用UIAppearance API的阴影或选择哪个导航栏必须隐藏/显示使用故事板(或源代码)的阴影。这是扩展:

import UIKit

private var flatAssociatedObjectKey: UInt8 = 0

/*
  An extension that adds a "flat" field to UINavigationBar. This flag, when
  enabled, removes the shadow under the navigation bar.
 */
@IBDesignable extension UINavigationBar {
    @IBInspectable var flat: Bool {
        get {
            guard let obj = objc_getAssociatedObject(self, &flatAssociatedObjectKey) as? NSNumber else {
                return false
            }
            return obj.boolValue;
        }

        set {
            if (newValue) {
                let void = UIImage()
                setBackgroundImage(void, forBarPosition: .Any, barMetrics: .Default)
                shadowImage = void
            } else {
                setBackgroundImage(nil, forBarPosition: .Any, barMetrics: .Default)
                shadowImage = nil
            }
            objc_setAssociatedObject(self, &flatAssociatedObjectKey, NSNumber(bool: newValue),
                    objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN_NONATOMIC)
        }
    }
}

现在，要禁用所有导航条上的阴影，你必须使用:

UINavigationBar.appearance().flat = true

或者你可以使用故事板启用/禁用此行为:

我的方法:

UINavigationBar.appearance().setBackgroundImage(
            UIImage(),
            forBarPosition: .Any,
            barMetrics: .Default)
    var _width:CGFloat! = self.navigationController?.navigationBar.layer.frame.width
            var _height:CGFloat! = self.navigationController?.navigationBar.layer.frame.height
            var navBarBg = UIView(frame:CGRectMake(0, 0, _width, _height))
            //solid color for bg
            navBarBg.backgroundColor = UIColor.orangeColor()
            view.addSubview(navBarBg)

Swift 4.2解决方案:

private func removeHairlineFromNavbar() {
    UINavigationBar.appearance().setBackgroundImage(
        UIImage(),
        for: .any,
        barMetrics: .default)
    UINavigationBar.appearance().shadowImage = UIImage()
}

把这个函数放在第一个Viewcontroller，然后在viewdidload中调用它