How to remove border of the navigationBar in swift?

Question

The trouble is with these two lines:

self.navigationController?.navigationBar.setBackgroundImage(UIImage(named: ""), forBarMetrics: UIBarMetrics.Default)
self.navigationController?.navigationBar.shadowImage = UIImage(named: "")

Since you don't have an image with no name, UIImage(named: "") returns nil, which means the default behavior kicks in:

When non-nil, a custom shadow image to show instead of the default shadow image. For a custom shadow to be shown, a custom background image must also be set with -setBackgroundImage:forBarMetrics: (if the default background image is used, the default shadow image will be used).

You need a truly empty image, so just initialize with UIImage():

self.navigationController?.navigationBar.setBackgroundImage(UIImage(), for: UIBarMetrics.default)
self.navigationController?.navigationBar.shadowImage = UIImage()

Swift 4 & Swift 5

Removing border:

self.navigationController?.navigationBar.setBackgroundImage(UIImage(), for:.default)
self.navigationController?.navigationBar.shadowImage = UIImage()
self.navigationController?.navigationBar.layoutIfNeeded()

Restoring border:

self.navigationController?.navigationBar.setBackgroundImage(nil, for:.default)
self.navigationController?.navigationBar.shadowImage = nil
self.navigationController?.navigationBar.layoutIfNeeded()

With Swift 2 you can do it this way:

AppDelegate file

Inside func application(..., didFinishLaunchingWithOptions launchOptions:...)

UINavigationBar.appearance().shadowImage = UIImage()
UINavigationBar.appearance().setBackgroundImage(UIImage(), forBarMetrics: .Default)

for Swift 3:

UINavigationBar.appearance().shadowImage = UIImage()
UINavigationBar.appearance().setBackgroundImage(UIImage(), for: .default)

Just write this in the extension of UINavigationBar

extension UINavigationBar {

    func shouldRemoveShadow(_ value: Bool) -> Void {
        if value {
            self.setValue(true, forKey: "hidesShadow")
        } else {
            self.setValue(false, forKey: "hidesShadow")
        }
    }
}

And in your viewController...

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    self.navigationController?.navigationBar.shouldRemoveShadow(true)        
}

And to get this undone for any viewController, just pass false.

this will remove the shadow image altogether

for parent in self.navigationController!.navigationBar.subviews {
 for childView in parent.subviews {
     if(childView is UIImageView) {
         childView.removeFromSuperview()
     }
 }
}

Swift 5

When using setBackgroundImage / shadowImage to hide the hairline, there's a slight delay. This method removes the delay. Credit to Chameleon Framework. This is the method they use (in ObjC)

extension UINavigationController {
    func hideHairline() {
        if let hairline = findHairlineImageViewUnder(navigationBar) {
            hairline.isHidden = true
        }
    }
    func restoreHairline() {
        if let hairline = findHairlineImageViewUnder(navigationBar) {
            hairline.isHidden = false
        }
    }
    func findHairlineImageViewUnder(_ view: UIView) -> UIImageView? {
        if view is UIImageView && view.bounds.size.height <= 1.0 {
            return view as? UIImageView
        }
        for subview in view.subviews {
            if let imageView = self.findHairlineImageViewUnder(subview) {
                return imageView
            }
        }
        return nil
    }
}

Set barStyle to .Black before setting the tint:

self.navigationController?.navigationBar.translucent = false
self.navigationController?.navigationBar.barStyle = .Black
self.navigationController?.navigationBar.barTintColor = UIColor.blueColor()