Fully customizable 🎨 tab bar without using storyboard or .xib files for IOS written by Swift 4

UICTabbarViewController.swift

//
//  ViewController.swift
//  UICTabbar
//
//  Created by Coder ACJHP on 2.04.2019.
//  Copyright © 2019 Onur Işık. All rights reserved.
//

import UIKit

let showBadge = Notification.Name.init("showBadge")

class UICTabbarViewController: UIViewController {

    private var buttonsStackView: UIStackView?
    private var tabButtonLabelsList = [UILabel]()
    private var tabButtonBadgeLabelsList = [UILabel]()
    private var tabButtonContainerViewList = [UIView]()
    private var tabButtonImageViewList = [UIImageView]()
    private var previousContentViewController: UIViewController?
    
    public var tabbarView: UIView!
    public var tabbarHeight: CGFloat = 60
    public var tabNameSet = [String]()
    public var tabIconSet = [UIImage]()
    public var tabSelectedIconSet = [UIImage]()
    public var tabViewControllerSet = [UIViewController]()
    
    public var isGlowing: Bool = false {
        didSet {
            if isGlowing {
                selectedButtonBackgroundColor = .clear
            }
        }
    }
    public var glowColor: UIColor = .red
    public var selectedButtonTitleColor: UIColor = .darkGray
    public var unSelectedButtonTitleColor: UIColor = .white
    public var selectedButtonBackgroundColor: UIColor = .clear
    public var buttonTitleFont: UIFont = UIFont.boldSystemFont(ofSize: 12)
    
    public var backgroundImage: UIImage?
    private var tabbarBGImageView: UIImageView = {
        let screenDimension = UIScreen.main.bounds
        let imgView = UIImageView(frame: CGRect(x: 0, y: 0, width: screenDimension.width, height: 60))
        imgView.contentMode = .scaleAspectFill
        imgView.clipsToBounds = true
        return imgView
    }()
        
    override func viewDidLoad() {
        super.viewDidLoad()

        NotificationCenter.default.addObserver(self, selector: #selector(handleNotification(_:)), name: showBadge, object: nil)
    }
    
    @objc fileprivate func handleNotification(_ notification: Notification) {
        if let userInfo = notification.userInfo as? Dictionary<String, AnyObject> {
            guard let badgeIndex = userInfo["index"] as? Int else { return }
            let currentBadge = tabButtonBadgeLabelsList[badgeIndex]
            currentBadge.isHidden = false
            currentBadge.text = "1"
        }
    }
    
    // hide home indicator on iPhoneX group
    override var prefersHomeIndicatorAutoHidden: Bool { return true }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        // Create and initialize tabbar view
        createTabbar()
        
        // Set first button as selected
        animatePressedButton(UIButton())
        
        // Initialize content view controller
        let firstViewController = tabViewControllerSet.first!
        previousContentViewController = firstViewController
        displayContentController(content: firstViewController)
    }

    fileprivate func createTabbar() {
        
        // Create simple view than add stack view on it to be container
        // Stack view it's container for tab buttons
        // Tab buttons UIView -> UIImageView (for icon) + UILabel (for title) + UILabel (for badge) + UIButton (for press handling)
        let screenDimension = UIScreen.main.bounds
        tabbarView = UIView(frame: CGRect(x: 0, y: 0, width: screenDimension.width, height: tabbarHeight))
        tabbarView.backgroundColor = .purple
        tabbarView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(tabbarView)
        
        NSLayoutConstraint.activate([
            tabbarView.widthAnchor.constraint(equalTo: view.widthAnchor),
            tabbarView.heightAnchor.constraint(equalToConstant: tabbarHeight),
            tabbarView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
            tabbarView.centerXAnchor.constraint(equalTo: view.centerXAnchor)
        ])
        
        // Check if backgorund image is defined setup background image container
        if backgroundImage != nil {
            
            tabbarBGImageView.image = backgroundImage
            tabbarView.backgroundColor = .clear
            tabbarView.insertSubview(tabbarBGImageView, at: 0)
            
            tabbarBGImageView.translatesAutoresizingMaskIntoConstraints = false
            NSLayoutConstraint.activate([
                tabbarBGImageView.widthAnchor.constraint(equalTo: tabbarView.widthAnchor),
                tabbarBGImageView.heightAnchor.constraint(equalToConstant: tabbarHeight),
                tabbarBGImageView.bottomAnchor.constraint(equalTo: tabbarView.bottomAnchor),
                tabbarBGImageView.centerXAnchor.constraint(equalTo: tabbarView.centerXAnchor)
                ])
        }
        
        // Create stackView + tab bar buttons
        createTabbarButtons()
    }

    fileprivate func createTabbarButtons() {
        
        if buttonsStackView == nil {
            
            buttonsStackView = UIStackView(frame: tabbarView.frame)
            buttonsStackView?.alignment = .center
            buttonsStackView?.distribution = .equalSpacing
            buttonsStackView?.axis = .horizontal
            let estimatedLeftRightInset = tabbarView.frame.width * 0.04
            buttonsStackView?.layoutMargins = UIEdgeInsets(top: 0, left: estimatedLeftRightInset, bottom: 0, right: estimatedLeftRightInset)
            buttonsStackView?.isLayoutMarginsRelativeArrangement = true
            buttonsStackView?.translatesAutoresizingMaskIntoConstraints = false
            tabbarView.addSubview(buttonsStackView!)
            
            NSLayoutConstraint.activate([
                buttonsStackView!.widthAnchor.constraint(equalTo: tabbarView.widthAnchor),
                buttonsStackView!.heightAnchor.constraint(equalTo: tabbarView.heightAnchor),
                buttonsStackView!.centerXAnchor.constraint(equalTo: tabbarView.centerXAnchor),
                buttonsStackView!.centerYAnchor.constraint(equalTo: tabbarView.centerYAnchor)
            ])
            
            // Create buttons depended on icon set count
            for index in 0 ..< tabIconSet.count {
                
                // Button container view
                let containerView = UIView(frame: CGRect(x: 0, y: 0, width: tabbarHeight, height: tabbarHeight))
                containerView.backgroundColor = .clear
                tabButtonContainerViewList.append(containerView)
                containerView.translatesAutoresizingMaskIntoConstraints = false
                
                NSLayoutConstraint.activate([
                    containerView.widthAnchor.constraint(equalToConstant: tabbarHeight),
                    containerView.heightAnchor.constraint(equalToConstant: tabbarHeight)
                ])
                
                // Icon image view
                let iconView = UIImageView(image: tabIconSet[index])
                iconView.frame = CGRect(x: 0, y: 0, width: 30, height: 30)
                iconView.contentMode = .scaleAspectFit
                containerView.addSubview(iconView)
                iconView.center = CGPoint(x: containerView.center.x, y: containerView.center.y - 7)
                tabButtonImageViewList.append(iconView)
                
                // Badge label view
                let badgelabel = UILabel(frame: CGRect(x: tabbarHeight - 20, y: 5, width: 15, height: 15))
                badgelabel.backgroundColor = .red
                badgelabel.layer.cornerRadius = badgelabel.frame.width / 2
                badgelabel.layer.masksToBounds = true
                badgelabel.textColor = .white
                badgelabel.textAlignment = .center
                badgelabel.font = UIFont.boldSystemFont(ofSize: 11)
                badgelabel.isHidden = true
                containerView.addSubview(badgelabel)
                tabButtonBadgeLabelsList.append(badgelabel)
                
                // Title label view
                let nameLabel = UILabel(frame: CGRect(x: 0, y: containerView.frame.height - 22, width: containerView.frame.width, height: 22))
                nameLabel.font = buttonTitleFont
                nameLabel.textColor = unSelectedButtonTitleColor
                nameLabel.textAlignment = .center
                nameLabel.text = tabNameSet[index]
                containerView.addSubview(nameLabel)
                tabButtonLabelsList.append(nameLabel)
                
                // Hidden (transparent) button
                let button = UIButton(type: .system)
                button.frame = containerView.frame
                button.setTitle("", for: .normal)
                button.tag = index
                button.addTarget(self, action: #selector(handleButtonPress(_:)), for: .touchUpInside)
                containerView.addSubview(button)

                // Add button container to stack view
                buttonsStackView?.addArrangedSubview(containerView)
                buttonsStackView?.layoutIfNeeded()
            }
            
            buttonsStackView?.layoutSubviews()
        }
    }
    
    @objc fileprivate func handleButtonPress(_ sender: UIButton) {
        
        animatePressedButton(sender)
        showViewController(forIndex: sender.tag)
    }
    
    fileprivate func animatePressedButton(_ sender: UIButton) {
        
        tabButtonContainerViewList.forEach {
            $0.backgroundColor = .clear
            // Remove glow layer from the view
            if isGlowing { removeGlowAnimation(fromView: $0) }
        }
        
        // Pick selected button container view
        let view = tabButtonContainerViewList[sender.tag]
        view.alpha = 0
        
        UIView.transition(with: view, duration: 0.25, options: [.transitionCrossDissolve], animations: {

            view.alpha = 1.0
            view.backgroundColor = self.selectedButtonBackgroundColor
            
            // Revert all unselected icons to buttons
            for (index, item) in self.tabButtonImageViewList.enumerated() {
                item.transform = .identity
                item.image = self.tabIconSet[index]
            }
            
            // Hide badge if it's appear
            self.tabButtonBadgeLabelsList[sender.tag].isHidden = true
            
            // Make all button label text color to default
            self.tabButtonLabelsList.forEach {
                $0.textColor = self.unSelectedButtonTitleColor
                $0.font = self.buttonTitleFont
            }
            
            let label = self.tabButtonLabelsList[sender.tag]
            label.textColor = self.selectedButtonTitleColor
            label.font = self.buttonTitleFont.withSize(14)
            
            // Be sure to selected button icons not nil
            if self.tabSelectedIconSet.count > 0 {
                let imageView = self.tabButtonImageViewList[sender.tag]
                imageView.image = self.tabSelectedIconSet[sender.tag]
                imageView.transform = CGAffineTransform.init(scaleX: 1.2, y: 1.2)
            }
            
            // Apply glow animation if enabled
            if self.isGlowing { self.applyGlow(toView: view, withColor: self.glowColor) }
            
        }, completion: nil )
    }
    
    private func showViewController(forIndex index: Int) {
        
        if index < tabViewControllerSet.count && index > -1 {
            // remove old content view controller if exist
            hideContentController(content: previousContentViewController!)
            
            // add new content view controller
            let currentViewController = tabViewControllerSet[index]
            previousContentViewController = currentViewController
            displayContentController(content: currentViewController)
        } else {
            debugPrint("Given index out of bounds!")
        }
    }
    
    private func displayContentController(content: UIViewController) {
        self.addChild(content)
        // Change size content view controller to fit the container view controller size
        content.view.frame = CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height - tabbarHeight)
        self.view.addSubview(content.view)
        content.didMove(toParent: self)
    }
    
    private func hideContentController(content: UIViewController) {
        content.willMove(toParent: nil)
        content.view.removeFromSuperview()
        content.removeFromParent()
    }
    
    private func applyGlow(toView: UIView, withColor: UIColor) {
        
        toView.layer.shadowPath = CGPath(roundedRect: toView.bounds, cornerWidth: 5, cornerHeight: 5, transform: nil)
        toView.layer.shadowColor = withColor.cgColor
        toView.layer.shadowOffset = CGSize.zero
        toView.layer.shadowRadius = 10
        toView.layer.shadowOpacity = 1
    }
    
    private func removeGlowAnimation(fromView: UIView) {
        
        fromView.layer.shadowPath = nil
        fromView.layer.shadowColor = UIColor.clear.cgColor
        fromView.layer.shadowOffset = CGSize.zero
        fromView.layer.shadowRadius = 0
        fromView.layer.shadowOpacity = 0
    }
}

How to implement it?

From View controller

override func viewDidLoad() {
        super.viewDidLoad()

        let coderTabbarViewController = UICTabbarViewController()
        coderTabbarViewController.tabIconSet = // assign your own image list [UIImage]
        coderTabbarViewController.tabNameSet = // assign your own name list [String]
        coderTabbarViewController.tabViewControllerSet = // assign your own VC list [UIViewController]
        self.present(coderTabbarViewController, animated: true, completion: nil)
    }

Or you can call it directly from appDelegate class as rootViewController

Properties that you can customize it as you like:
1- Tabbar background color (default value = purple)
2- Tabbar background image (default value = nil)
3- Tabbar selected button background color (default value = clear)
4- Tabbar selected button glow effect (default value = false)
5- Tabbar titles font size and colors (on selected & unselected) (default value = white & 12 bold)
6- Tabbar selected icons (change icon when tab button is selected) (default value = nil)
7- Add badge to tabbar button {
(You can show badge by sending notification with name "showBadge" and userInfo["index": IndexNumberOfTab])
For example:

// From any where in your application
 NotificationCenter.default.post(name: showBadge, object: nil, userInfo: ["index": 2]) 

}

It's look like this: