pxpgraphics的解决方案为Swift 2.0更新

extension UINavigationBar {

    func hideBottomHairline()
    {
        hairlineImageViewInNavigationBar(self)?.hidden = true
    }

    func showBottomHairline()
    {
        hairlineImageViewInNavigationBar(self)?.hidden = false
    }

    private func hairlineImageViewInNavigationBar(view: UIView) -> UIImageView?
    {
        if let imageView = view as? UIImageView where imageView.bounds.height <= 1
        {
            return imageView
        }

        for subview: UIView in view.subviews
        {
            if let imageView = hairlineImageViewInNavigationBar(subview)
            {
                return imageView
            }
        }

        return nil
    }

}

extension UIToolbar
{

    func hideHairline()
    {
        let navigationBarImageView = hairlineImageViewInToolbar(self)?.hidden = true
    }

    func showHairline()
    {
        let navigationBarImageView = hairlineImageViewInToolbar(self)?.hidden = false
    }

    private func hairlineImageViewInToolbar(view: UIView) -> UIImageView?
    {
        if let imageView = view as? UIImageView where imageView.bounds.height <= 1
        {
            return imageView
        }

        for subview: UIView in view.subviews
        {
            if let imageView = hairlineImageViewInToolbar(subview)
            {
                return imageView
            }
        }

        return nil
    }

}

我刚刚为这个创建了一个扩展…关于格式的问题很抱歉(这是我的第一个答案)。

用法:

  override func viewDidLoad() {
    super.viewDidLoad()
    self.navigationController?.hideShadow = true
}

扩展:

 UINavigationController.swift
//  Created by Ricardo López Rey on 16/7/15.

import Foundation


struct UINavigationControllerExtension {
    static var hideShadowKey : String = "HideShadow"
static let backColor = UIColor(red: 247/255, green: 247/255, blue: 248/255, alpha: 1.0)
}

extension UINavigationController {

    var hideShadow : Bool {
        get {
            if let ret =  objc_getAssociatedObject(self, &UINavigationControllerExtension.hideShadowKey) as? Bool {
                return ret
            } else {
                return false
            }


        }
        set {
            objc_setAssociatedObject(self,&UINavigationControllerExtension.hideShadowKey,newValue, objc_AssociationPolicy(OBJC_ASSOCIATION_RETAIN_NONATOMIC))

            if newValue {


            self.navigationBar.setBackgroundImage(solidImage(UINavigationControllerExtension.backColor), forBarMetrics: UIBarMetrics.Default)

                self.navigationBar.shadowImage = solidImage(UIColor.clearColor())
            } else {
                self.navigationBar.setBackgroundImage(nil, forBarMetrics: UIBarMetrics.Default)
            }
        }
    }

    private func solidImage(color: UIColor, size: CGSize = CGSize(width: 1,height: 1)) -> UIImage {
        var rect = CGRectMake(0, 0, size.width, size.height)
        UIGraphicsBeginImageContextWithOptions(size, false, 0)
        color.setFill()
        UIRectFill(rect)
        var image: UIImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return image
    }


}

想把Serhii回答的Swift版本加进去。我用下面的代码创建了一个uibareextension .swift:

import Foundation
import UIKit

extension UINavigationBar {
    func hideBottomHairline() {
        self.hairlineImageView?.isHidden = true
    }

    func showBottomHairline() {
        self.hairlineImageView?.isHidden = false
    }
}

extension UIToolbar {
    func hideBottomHairline() {
        self.hairlineImageView?.isHidden = true
    }

    func showBottomHairline() {
        self.hairlineImageView?.isHidden = false
    }
}

extension UIView {
    fileprivate var hairlineImageView: UIImageView? {
        return hairlineImageView(in: self)
    }

    fileprivate func hairlineImageView(in view: UIView) -> UIImageView? {
        if let imageView = view as? UIImageView, imageView.bounds.height <= 1.0 {
            return imageView
        }

        for subview in view.subviews {
            if let imageView = self.hairlineImageView(in: subview) { return imageView }
        }

        return nil
    }
}

设置背景图像的问题是它消除了模糊。您可以在不设置背景图像的情况下删除它。在这里看到我的答案。

对于iOS 13:

使用.shadowColor属性

如果此属性为nil或包含透明颜色，则该栏不显示阴影

例如:

let navigationBar = navigationController?.navigationBar
let navigationBarAppearance = UINavigationBarAppearance()
navigationBarAppearance.shadowColor = .clear
navigationBar?.scrollEdgeAppearance = navigationBarAppearance

对于iOS 12及以下版本:

为此，您应该设置一个自定义阴影图像。但是为了显示阴影图像，你还需要设置一个自定义背景图像，引用自苹果的文档:

要显示自定义阴影图像，必须有自定义背景图像 也可以使用setBackgroundImage(_:for:)方法进行设置。如果默认 使用背景图像，然后将使用默认阴影图像 不管这个属性的值。

So:

let navigationBar = navigationController!.navigationBar
navigationBar.setBackgroundImage(#imageLiteral(resourceName: "BarBackground"),
                                                        for: .default)
navigationBar.shadowImage = UIImage()

以上是唯一的“官方”隐藏方法。不幸的是，它消除了杆的半透明。

我不需要背景图像，只是颜色##

你有这些选择:

纯色，无半透明: navigationBar。barTintColor = uiccolor . redcolor () navigationBar。isstranslucent = false navigationBar.setBackgroundImage(UIImage()， for: .default) navigationBar。shadowImage = UIImage() 创建小背景图像充满颜色和使用它。 使用下面描述的“hack”方法。它也将保持酒吧半透明。

如何保持酒吧的半透明?# #

为了保持半透明，你需要另一种方法，它看起来像一个黑客，但工作得很好。我们试图移除的阴影是UINavigationBar下面的一个发际线UIImageView。我们可以找到它，并在需要时隐藏/显示它。

下面的说明假设你只需要在UINavigationController层次结构的一个控制器中隐藏发际线。

Declare instance variable: private var shadowImageView: UIImageView? Add method which finds this shadow (hairline) UIImageView: private func findShadowImage(under view: UIView) -> UIImageView? { if view is UIImageView && view.bounds.size.height <= 1 { return (view as! UIImageView) } for subview in view.subviews { if let imageView = findShadowImage(under: subview) { return imageView } } return nil } Add/edit viewWillAppear/viewWillDisappear methods: override func viewWillAppear(_ animated: Bool) { super.viewWillAppear(animated) if shadowImageView == nil { shadowImageView = findShadowImage(under: navigationController!.navigationBar) } shadowImageView?.isHidden = true } override func viewWillDisappear(_ animated: Bool) { super.viewWillDisappear(animated) shadowImageView?.isHidden = false }

同样的方法也适用于UISearchBar发际线， 以及(几乎)任何你需要隐藏的东西:)

非常感谢@Leo Natan的原创想法!

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)