UIBarButtonItem with badge, Swift 4, iOS 9/10/11

BadgeBarButtonItem.swift

import UIKit

public class BadgeBarButtonItem: UIBarButtonItem
{
    @IBInspectable
    public var badgeNumber: Int = 0 {
        didSet {
            self.updateBadge()
        }
    }
    
    private let label: UILabel
    
    required public init?(coder aDecoder: NSCoder)
    {
        let label = UILabel()
        label.backgroundColor = .red
        label.alpha = 0.9
        label.layer.cornerRadius = 9
        label.clipsToBounds = true
        label.isUserInteractionEnabled = false
        label.translatesAutoresizingMaskIntoConstraints = false
        label.textAlignment = .center
        label.textColor = .white
        label.layer.zPosition = 1
        self.label = label
        
        super.init(coder: aDecoder)
        
        self.addObserver(self, forKeyPath: "view", options: [], context: nil)
    }
    
    override public func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?)
    {
        self.updateBadge()
    }
    
    private func updateBadge()
    {
        guard let view = self.value(forKey: "view") as? UIView else { return }
        
        self.label.text = "\(badgeNumber)"
        
        if self.badgeNumber > 0 && self.label.superview == nil
        {
            view.addSubview(self.label)
            
            self.label.widthAnchor.constraint(equalToConstant: 18).isActive = true
            self.label.heightAnchor.constraint(equalToConstant: 18).isActive = true
            self.label.centerXAnchor.constraint(equalTo: view.centerXAnchor, constant: 9).isActive = true
            self.label.centerYAnchor.constraint(equalTo: view.centerYAnchor, constant: -9).isActive = true
        }
        else if self.badgeNumber == 0 && self.label.superview != nil
        {
            self.label.removeFromSuperview()
        }
    }
    
    deinit {
        self.removeObserver(self, forKeyPath: "view")
    }
}

If someone wants to know about the steps to use this in .storyboard
here are the steps,

1. Download "BadgeBarButtonItem.swift" and Drag/ Add it in scope of your project with xCode open.
2. Tell your bar button to be an object of type BadgeBarButtonItem in Identity Inspector
3. Then you can set some other properties from .storyboard going to Attributes Inspector

how to use Programmatically?

Very nice thanks!

it is so simple...

set badgeNumber Property

ex.

let countValue = 3

self.buttonName.badgeNumber = countValue

thanks it works with swift 4.2

We can use it as

let badgeBtn = BadgeBarButtonItem(image: UIImage(named: "notification"), style: .plain, target: self, action: #selector(notificationBtnClick))
badgeBtn?.badgeNumber = 4

    self.navigationItem.rightBarButtonItems = [badgeBtn,barBtn]

The above code is giving error like "Extra argument 'image' in call "

The above code is giving error like "Extra argument 'image' in call "

The above code is giving error like "Extra argument 'image' in call "

Thanks for this code. There was one problem, that it won't work for numbers greater than 9. I had to modify the code a bit like this:

        let size = CGFloat(badgeNumber < 10 ? 18 : 26)
        let radius = CGFloat(badgeNumber < 10 ? 9 : 13)

        self.label.layer.cornerRadius = radius
        self.label.widthAnchor.constraint(equalToConstant: size).isActive = true
        self.label.heightAnchor.constraint(equalToConstant: size).isActive = true
        self.label.centerXAnchor.constraint(equalTo: view.centerXAnchor, constant: size/2).isActive = true
        self.label.centerYAnchor.constraint(equalTo: view.centerYAnchor, constant: -size/2).isActive = true

And removed the line self.label.layer.cornerRadius = 9 from required public init

Great job! Here is a version that keeps the UIBarButtonItem constructors intact and there is no need for observers.

public class BadgeBarButtonItem: UIBarButtonItem
{
    @IBInspectable
    public var badgeNumber: Int = 0 {
        didSet {
            self.updateBadge()
        }
    }
    
    private lazy var label: UILabel = {
        let label = UILabel()
        label.backgroundColor = .red
        label.alpha = 0.9
        label.layer.cornerRadius = 9
        label.clipsToBounds = true
        label.isUserInteractionEnabled = false
        label.translatesAutoresizingMaskIntoConstraints = false
        label.textAlignment = .center
        label.textColor = .white
        label.layer.zPosition = 1
        return label
    }()
    
    private func updateBadge()
    {
        guard let view = self.value(forKey: "view") as? UIView else { return }
        
        self.label.text = "\(badgeNumber)"
        
        if self.badgeNumber > 0 && self.label.superview == nil
        {
            view.addSubview(self.label)
            
            self.label.widthAnchor.constraint(equalToConstant: 18).isActive = true
            self.label.heightAnchor.constraint(equalToConstant: 18).isActive = true
            self.label.centerXAnchor.constraint(equalTo: view.centerXAnchor, constant: 9).isActive = true
            self.label.centerYAnchor.constraint(equalTo: view.centerYAnchor, constant: -9).isActive = true
        }
        else if self.badgeNumber == 0 && self.label.superview != nil
        {
            self.label.removeFromSuperview()
        }
    }
}

You can use it this way:

let item = BadgeBarButtonItem(image: UIImage(named: "some_image")),
                                   style: .plain,
                                   target: self,
                                   action: #selector(someAction))

navigationItem.rightBarButtonItem = item

not work!

not show bubble

i know why bubble is not showing reason

guard let view = self.value(forKey: "view") as? UIView else { return }

this statement is only called with else condition