UIBarButtonItem+Badge.swift

//
//  UIBarButtonItem+Badge.swift
//  PiGuardMobile
//
//  Created by Stefano Vettor on 12/04/16.
//  Copyright © 2016 Stefano Vettor. All rights reserved.
//

import UIKit

extension CAShapeLayer {
    private func drawCircleAtLocation(location: CGPoint, withRadius radius: CGFloat, andColor color: UIColor, filled: Bool) {
        fillColor = filled ? color.CGColor : UIColor.whiteColor().CGColor
        strokeColor = color.CGColor
        let origin = CGPoint(x: location.x - radius, y: location.y - radius)
        path = UIBezierPath(ovalInRect: CGRect(origin: origin, size: CGSize(width: radius * 2, height: radius * 2))).CGPath
    }
}

private var handle: UInt8 = 0;

extension UIBarButtonItem {
    
    private var badgeLayer: CAShapeLayer? {
        if let b: AnyObject = objc_getAssociatedObject(self, &handle) {
            return b as? CAShapeLayer
        } else {
            return nil
        }
    }
    
    func addBadge(number number: Int, withOffset offset: CGPoint = CGPoint.zero, andColor color: UIColor = UIColor.redColor(), andFilled filled: Bool = true) {
        guard let view = self.valueForKey("view") as? UIView else { return }
        
        badgeLayer?.removeFromSuperlayer()
        
        // Initialize Badge
        let badge = CAShapeLayer()
        let radius = CGFloat(7)
        let location = CGPoint(x: view.frame.width - (radius + offset.x), y: (radius + offset.y))
        badge.drawCircleAtLocation(location, withRadius: radius, andColor: color, filled: filled)
        view.layer.addSublayer(badge)
        
        // Initialiaze Badge's label
        let label = CATextLayer()
        label.string = "\(number)"
        label.alignmentMode = kCAAlignmentCenter
        label.fontSize = 11
        label.frame = CGRect(origin: CGPoint(x: location.x - 4, y: offset.y), size: CGSize(width: 8, height: 16))
        label.foregroundColor = filled ? UIColor.whiteColor().CGColor : color.CGColor
        label.backgroundColor = UIColor.clearColor().CGColor
        label.contentsScale = UIScreen.mainScreen().scale
        badge.addSublayer(label)
        
        // Save Badge as UIBarButtonItem property
        objc_setAssociatedObject(self, &handle, badge, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    }
    
    func updateBadge(number number: Int) {
        if let text = badgeLayer?.sublayers?.filter({ $0 is CATextLayer }).first as? CATextLayer {
            text.string = "\(number)"
        }
    }
    
    func removeBadge() {
        badgeLayer?.removeFromSuperlayer()
    }
    
}

Updated for Swift 3. It would be awesome if someone could make this support more than 1 number in the badge.

import UIKit

extension CAShapeLayer {
    func drawCircleAtLocation(location: CGPoint, withRadius radius: CGFloat, andColor color: UIColor, filled: Bool) {
        fillColor = filled ? color.cgColor : UIColor.white.cgColor
        strokeColor = color.cgColor
        let origin = CGPoint(x: location.x - radius, y: location.y - radius)
        path = UIBezierPath(ovalIn: CGRect(origin: origin, size: CGSize(width: radius * 2, height: radius * 2))).cgPath
    }
}

private var handle: UInt8 = 0;

extension UIBarButtonItem {
    private var badgeLayer: CAShapeLayer? {
        if let b: AnyObject = objc_getAssociatedObject(self, &handle) as AnyObject? {
            return b as? CAShapeLayer
        } else {
            return nil
        }
    }

    func addBadge(number: Int, withOffset offset: CGPoint = CGPoint.zero, andColor color: UIColor = UIColor.red, andFilled filled: Bool = true) {
        guard let view = self.value(forKey: "view") as? UIView else { return }

        badgeLayer?.removeFromSuperlayer()

        // Initialize Badge
        let badge = CAShapeLayer()
        let radius = CGFloat(7)
        let location = CGPoint(x: view.frame.width - (radius + offset.x), y: (radius + offset.y))
        badge.drawCircleAtLocation(location: location, withRadius: radius, andColor: color, filled: filled)
        view.layer.addSublayer(badge)

        // Initialiaze Badge's label
        let label = CATextLayer()
        label.string = "\(number)"
        label.alignmentMode = kCAAlignmentCenter
        label.fontSize = 11
        label.frame = CGRect(origin: CGPoint(x: location.x - 4, y: offset.y), size: CGSize(width: 8, height: 16))
        label.foregroundColor = filled ? UIColor.white.cgColor : color.cgColor
        label.backgroundColor = UIColor.clear.cgColor
        label.contentsScale = UIScreen.main.scale
        badge.addSublayer(label)

        // Save Badge as UIBarButtonItem property
        objc_setAssociatedObject(self, &handle, badge, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    }

    func updateBadge(number: Int) {
        if let text = badgeLayer?.sublayers?.filter({ $0 is CATextLayer }).first as? CATextLayer {
            text.string = "\(number)"
        }
    }

    func removeBadge() {
        badgeLayer?.removeFromSuperlayer()
    }
}

This one supports double digits, but not triple. Just a small change on the badge width and label offset, but I'll post the whole thing:

import UIKit

extension CAShapeLayer {
    func drawCircleAtLocation(location: CGPoint, withRadius radius: CGFloat, andColor color: UIColor, filled: Bool) {
        fillColor = filled ? color.cgColor : UIColor.white.cgColor
        strokeColor = color.cgColor
        let origin = CGPoint(x: location.x - radius, y: location.y - radius)
        path = UIBezierPath(ovalIn: CGRect(origin: origin, size: CGSize(width: radius * 2, height: radius * 2))).cgPath
    }
}

private var handle: UInt8 = 0;

extension UIBarButtonItem {
    private var badgeLayer: CAShapeLayer? {
        if let b: AnyObject = objc_getAssociatedObject(self, &handle) as AnyObject? {
            return b as? CAShapeLayer
        } else {
            return nil
        }
    }
    
    func addBadge(number: Int, withOffset offset: CGPoint = CGPoint.zero, andColor color: UIColor = UIColor.red, andFilled filled: Bool = true) {
        guard let view = self.value(forKey: "view") as? UIView else { return }
        
        badgeLayer?.removeFromSuperlayer()
        
        var badgeWidth = 8
        var numberOffset = 4
        
        if number > 9 {
            badgeWidth = 12
            numberOffset = 6
        }
        
        // Initialize Badge
        let badge = CAShapeLayer()
        let radius = CGFloat(7)
        let location = CGPoint(x: view.frame.width - (radius + offset.x), y: (radius + offset.y))
        badge.drawCircleAtLocation(location: location, withRadius: radius, andColor: color, filled: filled)
        view.layer.addSublayer(badge)
        
        // Initialiaze Badge's label
        let label = CATextLayer()
        label.string = "\(number)"
        label.alignmentMode = kCAAlignmentCenter
        label.fontSize = 11
        label.frame = CGRect(origin: CGPoint(x: location.x - CGFloat(numberOffset), y: offset.y), size: CGSize(width: badgeWidth, height: 16))
        label.foregroundColor = filled ? UIColor.white.cgColor : color.cgColor
        label.backgroundColor = UIColor.clear.cgColor
        label.contentsScale = UIScreen.main.scale
        badge.addSublayer(label)
        
        // Save Badge as UIBarButtonItem property
        objc_setAssociatedObject(self, &handle, badge, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    }
    
    func updateBadge(number: Int) {
        if let text = badgeLayer?.sublayers?.filter({ $0 is CATextLayer }).first as? CATextLayer {
            text.string = "\(number)"
        }
    }
    
    func removeBadge() {
        badgeLayer?.removeFromSuperlayer()
    }
}

Badge don't seem to work on UIBarButtonItem that are on UIToolbar, any ideas?

I've been searching for nearly a full day and implemented several others' attempts..This one is the best and easiest way!!! Thank you so much!!

I hate to ask, but how do I use this? I am new to IOS development. I have added the swift file and created a navigation button like this:

navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Add", style: .plain, target: self, action: #selector(lockedButton))

Not sure where I can use the addBadge method? I tried referencing it like this:

navigationItem.rightBarButtonItem = UIBarButtonItem.addBadge()

But there is a red line through the addBadge option as I type, and it doesn't like it if I add it in manually...

Ok, sorry, I found the answer. For anyone else looking, you need to reference the button in a variable and add the method on that...

navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Add", style: .plain, target: self, action: #selector(lockedButton))

	let rightBarButtons = self.navigationItem.rightBarButtonItems
	
	let lastBarButton = rightBarButtons?.last
	
	lastBarButton?.addBadge(number: 4)

This was a very useful starting point. I've taken the Swift 3 version and enhanced the function so it supports text (not just numbers). It also draws a rounded rectangle instead of a circle, to better support wider strings. The code dynamically calculates the badge size based on the badge text.

Finally, I've changed the signature to be setBadge. If the badge is null or empty, then the badge will be removed.

import UIKit

extension CAShapeLayer {
    func drawRoundedRect(rect: CGRect, andColor color: UIColor, filled: Bool) {
        fillColor = filled ? color.cgColor : UIColor.white.cgColor
        strokeColor = color.cgColor
        path = UIBezierPath(roundedRect: rect, cornerRadius: 7).cgPath
    }
}

private var handle: UInt8 = 0;

extension UIBarButtonItem {
    private var badgeLayer: CAShapeLayer? {
        if let b: AnyObject = objc_getAssociatedObject(self, &handle) as AnyObject? {
            return b as? CAShapeLayer
        } else {
            return nil
        }
    }
    
    func setBadge(text: String?, withOffsetFromTopRight offset: CGPoint = CGPoint.zero, andColor color:UIColor = UIColor.red, andFilled filled: Bool = true, andFontSize fontSize: CGFloat = 11)
    {
        badgeLayer?.removeFromSuperlayer()
        
        if (text == nil || text == "") {
            return
        }
        
        addBadge(text: text!, withOffset: offset, andColor: color, andFilled: filled)
    }
    
    private func addBadge(text: String, withOffset offset: CGPoint = CGPoint.zero, andColor color: UIColor = UIColor.red, andFilled filled: Bool = true, andFontSize fontSize: CGFloat = 11)
    {
        guard let view = self.value(forKey: "view") as? UIView else { return }
        
        var font = UIFont.systemFont(ofSize: fontSize)
        
        if #available(iOS 9.0, *) {
            font = UIFont.monospacedDigitSystemFont(ofSize: fontSize, weight: UIFontWeightRegular)
        }
        
        let badgeSize = text.size(attributes: [NSFontAttributeName: font])
        
        // Initialize Badge
        let badge = CAShapeLayer()

        let height = badgeSize.height;
        var width = badgeSize.width + 2 /* padding */
        
        //make sure we have at least a circle
        if (width < height) {
            width = height
        }

        //x position is offset from right-hand side
        let x = view.frame.width - width + offset.x
        
        let badgeFrame = CGRect(origin: CGPoint(x: x, y: offset.y), size: CGSize(width: width, height: height))
        
        badge.drawRoundedRect(rect: badgeFrame, andColor: color, filled: filled)
        view.layer.addSublayer(badge)
        
        // Initialiaze Badge's label
        let label = CATextLayer()
        label.string = text
        label.alignmentMode = kCAAlignmentCenter
        label.font = font
        label.fontSize = font.pointSize
        
        label.frame = badgeFrame
        label.foregroundColor = filled ? UIColor.white.cgColor : color.cgColor
        label.backgroundColor = UIColor.clear.cgColor
        label.contentsScale = UIScreen.main.scale
        badge.addSublayer(label)
        
        // Save Badge as UIBarButtonItem property
        objc_setAssociatedObject(self, &handle, badge, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    }
    
    private func removeBadge() {
        badgeLayer?.removeFromSuperlayer()
    }
}

I have tested with Xcode 8 and Swift 3. When device orientation changes, badge is removed. I checked the view hierarchy and observed that badge is gone. I hope someone writes a fix for that.

Thanks guys, very useful.

@tosbaha
if you put the code of addBadge inside viewDidLayoutSubviews() it will work fine with orientation

thanks its work fine.

I needed same thing for a regular UIButton,

extension UIButton
{
    private var badgeLayer: CAShapeLayer? {
        if let b: AnyObject = objc_getAssociatedObject(self, &handle) as AnyObject? {
            return b as? CAShapeLayer
        } else {
            return nil
        }
    }
    
    func addBadge(number: Int, withOffset offset: CGPoint = CGPoint.zero, andColor color: UIColor = UIColor.red, andFilled filled: Bool = true , addedView:UIView?) {
        guard let view = addedView else { return }
        
        badgeLayer?.removeFromSuperlayer()
        
        var badgeWidth = 8
        var numberOffset = 4
        
        if number > 9 {
            badgeWidth = 12
            numberOffset = 6
        }
        
        // Initialize Badge
        let badge = CAShapeLayer()
        let radius = CGFloat(7)
        let location = CGPoint(x: view.frame.width - (radius + offset.x), y: (radius + offset.y))
        badge.drawCircleAtLocation(location: location, withRadius: radius, andColor: color, filled: filled)
        view.layer.addSublayer(badge)
        
        // Initialiaze Badge's label
        let label = CATextLayer()
        label.string = "\(number)"
        label.alignmentMode = kCAAlignmentCenter
        label.fontSize = 11
        label.frame = CGRect(origin: CGPoint(x: location.x - CGFloat(numberOffset), y: offset.y), size: CGSize(width: badgeWidth, height: 16))
        label.foregroundColor = filled ? UIColor.white.cgColor : color.cgColor
        label.backgroundColor = UIColor.clear.cgColor
        label.contentsScale = UIScreen.main.scale
        badge.addSublayer(label)
        
        // Save Badge as UIButtonItem property
        objc_setAssociatedObject(self, &handle, badge, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    }
    
    func updateBadge(number: Int) {
        if let text = badgeLayer?.sublayers?.filter({ $0 is CATextLayer }).first as? CATextLayer {
            text.string = "\(number)"
        }
    }
    
    func removeBadge() {
        badgeLayer?.removeFromSuperlayer()
    }

}

then wherever

    override func viewDidLoad() {
        super.viewDidLoad()
        button.tag = tagNumber   
    }

then

                  if let foundView = self.button.superView.viewWithTag(tagNumber) {
                    self.button.addBadge(number: 2, addedView: foundView)
                }

Hi all,

after doing this in viewDidLoad (and adding the extension code), i can see the bar button item in the navigation bar but not the badge :(

let inboxButton:UIBarButtonItem = UIBarButtonItem(image: UIImage(named: "inbox"), style: .plain, target: self, action: #selector(presentInbox))
let point = CGPoint(x: 0, y: 0)
inboxButton.addBadge(number: 2, withOffset: point, andColor: UIColor.black, andFilled: false)
self.navigationItem.leftBarButtonItem = inboxButton

Has someone a simple working example? Thank you very much Guys :)

https://gist.github.com/mohn93/bd950eeed82749b2ecad40ba3d4d0f1d

This fork has more features, hope it helps

Swift 4 version of the same

import UIKit

extension CAShapeLayer {
    func drawRoundedRect(rect: CGRect, andColor color: UIColor, filled: Bool) {
        fillColor = filled ? color.cgColor : UIColor.white.cgColor
        strokeColor = color.cgColor
        path = UIBezierPath(roundedRect: rect, cornerRadius: 7).cgPath
    }
}

private var handle: UInt8 = 0;

extension UIBarButtonItem {
    private var badgeLayer: CAShapeLayer? {
        if let b: AnyObject = objc_getAssociatedObject(self, &handle) as AnyObject? {
            return b as? CAShapeLayer
        } else {
            return nil
        }
    }
    
    func setBadge(text: String?, withOffsetFromTopRight offset: CGPoint = CGPoint.zero, andColor color:UIColor = UIColor.red, andFilled filled: Bool = true, andFontSize fontSize: CGFloat = 11)
    {
        badgeLayer?.removeFromSuperlayer()
        
        if (text == nil || text == "") {
            return
        }
        
        addBadge(text: text!, withOffset: offset, andColor: color, andFilled: filled)
    }
    
    private func addBadge(text: String, withOffset offset: CGPoint = CGPoint.zero, andColor color: UIColor = UIColor.red, andFilled filled: Bool = true, andFontSize fontSize: CGFloat = 11)
    {
        guard let view = self.value(forKey: "view") as? UIView else { return }
        
        var font = UIFont.systemFont(ofSize: fontSize)
        
        if #available(iOS 9.0, *) {
            font = UIFont.monospacedDigitSystemFont(ofSize: fontSize, weight: UIFont.Weight.regular)
        }
        
        let badgeSize = text.size(withAttributes: [NSAttributedStringKey.font: font])
        
        // Initialize Badge
        let badge = CAShapeLayer()
        
        let height = badgeSize.height;
        var width = badgeSize.width + 2 /* padding */
        
        //make sure we have at least a circle
        if (width < height) {
            width = height
        }
        
        //x position is offset from right-hand side
        let x = view.frame.width - width + offset.x
        
        let badgeFrame = CGRect(origin: CGPoint(x: x, y: offset.y), size: CGSize(width: width, height: height))
        
        badge.drawRoundedRect(rect: badgeFrame, andColor: color, filled: filled)
        view.layer.addSublayer(badge)
        
        // Initialiaze Badge's label
        let label = CATextLayer()
        label.string = text
        label.alignmentMode = kCAAlignmentCenter
        label.font = font
        label.fontSize = font.pointSize
        
        label.frame = badgeFrame
        label.foregroundColor = filled ? UIColor.white.cgColor : color.cgColor
        label.backgroundColor = UIColor.clear.cgColor
        label.contentsScale = UIScreen.main.scale
        badge.addSublayer(label)
        
        // Save Badge as UIBarButtonItem property
        objc_setAssociatedObject(self, &handle, badge, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    }
    
    private func removeBadge() {
        badgeLayer?.removeFromSuperlayer()
    }
}

Has anyone been able to use this with xcode 9?

This code does not work anymore:
guard let view = self.value(forKey: "view") as? UIView else { return }

works for me 9.0.1

** #guard let view = self.value(forKey: "view") as? UIView else { return }** here view is getting value nil because of which it does not show badge how do i fix this?

@zeeip6, I faced the same issue. It guess the name of the key for view might be changed to something else and because of this its returning nil. The workaround I did for that was to use customView as below

guard let view = self.customView else { return }

and initialize a BarButtonItem by giving an UIButton as its custom view.

let bellButton = UIButton(type: .custom)
bellButton.setBackgroundImage(UIImage(named:"notification"), for: .normal)
bellButton.addTarget(self, action: #selector(didClickNotificationButton(_:)), for: .touchUpInside)

let notificationBarButton = UIBarButtonItem(customView: bellButton)

Note: Offset needs to be adjusted as required when adding a badge.

@febinfathah code is working, but in my case badge was a truncated a bit from the top and I had to add an offset, not a big deal. But then I realized that badge is drawing behind icon, which is unacceptable. I fixed it by adding the following line on the bottom off "addBadge":

badge.zPosition = 1000

So, the new code is:

import UIKit

extension CAShapeLayer {
    
    func drawRoundedRect(rect: CGRect, andColor color: UIColor, filled: Bool) {
        fillColor = filled ? color.cgColor : UIColor.white.cgColor
        strokeColor = color.cgColor
        path = UIBezierPath(roundedRect: rect, cornerRadius: 7).cgPath
    }
    
}

private var handle: UInt8 = 0;

extension UIBarButtonItem {
    
    private var badgeLayer: CAShapeLayer? {
        if let b: AnyObject = objc_getAssociatedObject(self, &handle) as AnyObject? {
            return b as? CAShapeLayer
        } else {
            return nil
        }
    }
    
    func setBadge(text: String?, withOffsetFromTopRight offset: CGPoint = CGPoint.zero, andColor color:UIColor = UIColor.red, andFilled filled: Bool = true, andFontSize fontSize: CGFloat = 11) {
        badgeLayer?.removeFromSuperlayer()
        
        if (text == nil || text == "") {
            return
        }
        
        addBadge(text: text!, withOffset: offset, andColor: color, andFilled: filled)
    }
    
    private func addBadge(text: String, withOffset offset: CGPoint = CGPoint.zero, andColor color: UIColor = UIColor.red, andFilled filled: Bool = true, andFontSize fontSize: CGFloat = 11) {
        guard let view = self.value(forKey: "view") as? UIView else { return }
        
        var font = UIFont.systemFont(ofSize: fontSize)
        
        if #available(iOS 9.0, *) {
            font = UIFont.monospacedDigitSystemFont(ofSize: fontSize, weight: UIFont.Weight.regular)
        }
        
        let badgeSize = text.size(withAttributes: [NSAttributedStringKey.font: font])
        
        //initialize Badge
        let badge = CAShapeLayer()
        
        let height = badgeSize.height;
        var width = badgeSize.width + 2 /* padding */
        
        //make sure we have at least a circle
        if (width < height) {
            width = height
        }
        
        //x position is offset from right-hand side
        let x = view.frame.width - width + offset.x
        
        let badgeFrame = CGRect(origin: CGPoint(x: x, y: offset.y), size: CGSize(width: width, height: height))
        
        badge.drawRoundedRect(rect: badgeFrame, andColor: color, filled: filled)
        view.layer.addSublayer(badge)
        
        //initialiaze Badge's label
        let label = CATextLayer()
        label.string = text
        label.alignmentMode = kCAAlignmentCenter
        label.font = font
        label.fontSize = font.pointSize
        
        label.frame = badgeFrame
        label.foregroundColor = filled ? UIColor.white.cgColor : color.cgColor
        label.backgroundColor = UIColor.clear.cgColor
        label.contentsScale = UIScreen.main.scale
        badge.addSublayer(label)
        
        //save Badge as UIBarButtonItem property
        objc_setAssociatedObject(self, &handle, badge, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
        
        //bring layer to front
        badge.zPosition = 1000
    }
    
    private func removeBadge() {
        badgeLayer?.removeFromSuperlayer()
    }
    
}

Tested on both iPhone and iPad with iOS 11.1. Maintains its appearance after changing orientation as well.

Hello guys, I was trying to implement this using Xamarin but I always stop here because the view returned is always null. Am I missing out something or do I not understand how swift works? Here's where the error is and my c# implementation of that same code.
Swift
guard let view = self.value(forKey: "view") as? UIView else { return }
C#
var view = this.ValueForKey((Foundation.NSString)"view") as UIView;
if (view==null) return;

Hi,
Any of you have solved this.
guard let view = self.value(forKey: "view") as? UIView else { return }
This always returns a null value (Swift 3).
thank you.

guard let view = self.value(forKey: "view") as? UIView else { return }
This code will always return nil, if you set the badge in the wrong spot.

So if you want to display the badge, you would have to set the badge outside of viewDidLoad and you should see the badge. It seems setting the badge in viewDidAppear works for me there.

If you have been setting the badge in viewDidLoad, in iOS11 it handles it differently. Any related UI work will break or wont work. Try setting the badge outside of viewDidLoad and see if that works.

I hope this helps

As others have mentioned the view will be nil if you set the badge on viewDidLoad on iOS 11 and Xcode 9. To solve this just set the badge to the bar button Item in the " viewDidAppear" function.

Thank you all for the solution, neat and concise.

Instead of global handle var, it is better to use static struct, IMHO

private struct AssociatedKey {
        static var badgeLayer = "badgeLayer"
    }

    fileprivate var badgeLayer: CAShapeLayer? {
        get {
            return objc_getAssociatedObject(self, &AssociatedKey.badgeLayer) as? CAShapeLayer
        }
        set {
            if let newValue = newValue {
                objc_setAssociatedObject(
                    self,
                    &AssociatedKey.badgeLayer,
                    newValue as CAShapeLayer?,
                    .OBJC_ASSOCIATION_RETAIN_NONATOMIC
                )
            }
        }
    }

Does anyone know why this doesn't work with back button?

Its not working in Swift4.

Different approach and works with Swift 4 and various view controller states: https://gist.github.com/yonat/75a0f432d791165b1fd6

I have used this for tabItem but I want to show the layer on top of tabImage but layer is added behind it. Any way through which it can be attained?

This doesn't work unless it is a custom uibarbutton unforunately. :(

I have used this for tabItem but I want to show the layer on top of tabImage but layer is added behind it. Any way through which it can be attained?

u can get it by the property "badgeLayer"

This doesn't work unless it is a custom uibarbutton unforunately. :(

u can extension a button to do it , c the #ugenlik comment

swift 4.2

extension CAShapeLayer {
    func drawCircleAtLocation(location: CGPoint, withRadius radius: CGFloat, andColor color: UIColor, filled: Bool) {
        fillColor = filled ? color.cgColor : UIColor.white.cgColor
        strokeColor = color.cgColor
        let origin = CGPoint(x: location.x - radius, y: location.y - radius)
        path = UIBezierPath(ovalIn: CGRect(origin: origin, size: CGSize(width: radius * 2, height: radius * 2))).cgPath
    }
}

private var handle: UInt8 = 0;

extension UIBarButtonItem {
    private var badgeLayer: CAShapeLayer? {
        if let b: AnyObject = objc_getAssociatedObject(self, &handle) as AnyObject? {
            return b as? CAShapeLayer
        } else {
            return nil
        }
    }
    
    func addBadge(number: Int, withOffset offset: CGPoint = CGPoint.zero, andColor color: UIColor = UIColor.red, andFilled filled: Bool = true) {
        guard let view = self.value(forKey: "view") as? UIView else { return }
        
        badgeLayer?.removeFromSuperlayer()
        
        var badgeWidth = 8
        var numberOffset = 4
        
        if number > 9 {
            badgeWidth = 12
            numberOffset = 6
        }
        
        // Initialize Badge
        let badge = CAShapeLayer()
        let radius = CGFloat(7)
        let location = CGPoint(x: view.frame.width - (radius + offset.x), y: (radius + offset.y))
        badge.drawCircleAtLocation(location: location, withRadius: radius, andColor: color, filled: filled)
        view.layer.addSublayer(badge)
        
        // Initialiaze Badge's label
        let label = CATextLayer()
        label.string = "\(number)"
        label.alignmentMode = CATextLayerAlignmentMode.center
        label.fontSize = 11
        label.frame = CGRect(origin: CGPoint(x: location.x - CGFloat(numberOffset), y: offset.y), size: CGSize(width: badgeWidth, height: 16))
        label.foregroundColor = filled ? UIColor.white.cgColor : color.cgColor
        label.backgroundColor = UIColor.clear.cgColor
        label.contentsScale = UIScreen.main.scale
        badge.addSublayer(label)
        
        // Save Badge as UIBarButtonItem property
        objc_setAssociatedObject(self, &handle, badge, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    }
    
    func updateBadge(number: Int) {
        if let text = badgeLayer?.sublayers?.filter({ $0 is CATextLayer }).first as? CATextLayer {
            text.string = "\(number)"
        }
    }
    
    func removeBadge() {
        badgeLayer?.removeFromSuperlayer()
    }
}