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];

斯威夫特说

UINavigationBar.appearance().setBackgroundImage(UIImage(), forBarPosition: .Any, barMetrics: .Default)
UINavigationBar.appearance().shadowImage = UIImage()

in

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

Slightly Swift Solution 
func setGlobalAppearanceCharacteristics () {
    let navigationBarAppearace = UINavigationBar.appearance()
    navigationBarAppearace.tintColor = UIColor.white
    navigationBarAppearace.barTintColor = UIColor.blue
    navigationBarAppearace.setBackgroundImage(UIImage(), for: UIBarMetrics.default)
    navigationBarAppearace.shadowImage = UIImage()

}

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)

嗨，这适用于Swift 4。

    override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    self.navigationController?.navigationBar.shadowImage = UIImage()
    self.navigationController?.navigationBar.setBackgroundImage(UIImage(), for: .default)
    self.navigationController?.navigationBar.isTranslucent = false
}

你需要把这个放在viewDidLayoutSubviews而不是viewDidLoad

我知道这是一个老话题，但我找到了一个非常有效的解决方案:

子类UINavigationBar。 在你的UINavigationBar子类中，用下面的代码重写didAddSubview:

- (void)didAddSubview:(UIView *)subview
{
    [super didAddSubview:subview];

    if ([subview isKindOfClass:[UIImageView class]]) {
        [subview setClipsToBounds:YES];
    }
}