How to set UiSearchBar Search icon on the right side in swift

In ViewController, leftview of searchbar textfield is the actual search icon, so make it to nil and create a image view with custom icon and set as a right view of search textfield.

Objective C

@interface FirstViewController ()
{
    UISearchBar  *searchBar;
}
@end

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    searchBar = [[UISearchBar alloc] init];
    searchBar.frame = CGRectMake(15, 100, 350,50);

    [self.view addSubview:searchBar];
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];

    UITextField *searchTextField = [((UITextField *)[searchBar.subviews objectAtIndex:0]).subviews lastObject];
    searchTextField.layer.cornerRadius = 15.0f;
    searchTextField.textAlignment = NSTextAlignmentLeft;

    UIImage *image = [UIImage imageNamed:@"search"];
    UIImageView *imageView = [[UIImageView alloc] initWithImage:image];

    searchTextField.leftView = nil;

    searchTextField.placeholder = @"Search";

    searchTextField.rightView = imageView;
    searchTextField.rightViewMode = UITextFieldViewModeAlways;
}

Swift

    private var searchBar: UISearchBar!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        searchBar = UISearchBar()
        searchBar.frame = CGRect(x: 15, y: 100, width: 350, height: 50)
        self.view.addSubview(searchBar)

    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        let searchTextField:UITextField = searchBar.subviews[0].subviews.last as! UITextField
        searchTextField.layer.cornerRadius = 15
        searchTextField.textAlignment = NSTextAlignment.left
        let image:UIImage = UIImage(named: "search")!
        let imageView:UIImageView = UIImageView.init(image: image)
        searchTextField.leftView = nil
        searchTextField.placeholder = "Search"
        searchTextField.rightView = imageView
        searchTextField.rightViewMode = UITextFieldViewMode.always
    }

I suggest you to check Apple documentation layoutIfNeeded() and layoutSubviews() . You'll have better understanding after reading them. The magic happens when you write searchBar.layoutIfNeeded() instance method. Another solution is searchBar.layoutSubviews() but Apple documentation says:

You should not call this method directly. If you want to force a layout update, call the setNeedsLayout() method instead to do so prior to the next drawing update. If you want to update the layout of your views immediately, call the layoutIfNeeded() method.

According to @Jeyamahesan's answer. When you modify the code like below you do not need to separate the code in viewDidLoad() and ViewDidAppear().

Example:

import UIKit

class MainController: UIViewController {

    private var searchBar: UISearchBar!

    override func viewDidLoad() {
        super.viewDidLoad()

        searchBar = UISearchBar()
        searchBar.frame = CGRect(x: 15, y: 100, width: 350, height: 50)
        searchBar.layoutIfNeeded()
        self.view.addSubview(searchBar)

        let searchTextField:UITextField = searchBar.subviews[0].subviews.last as! UITextField
        searchTextField.layer.cornerRadius = 15
        searchTextField.textAlignment = NSTextAlignment.left
        let image:UIImage = UIImage(named: "Search")!
        let imageView:UIImageView = UIImageView.init(image: image)
        searchTextField.leftView = nil
        searchTextField.placeholder = "Search"
        searchTextField.rightView = imageView
        searchTextField.rightViewMode = UITextFieldViewMode.always
    }
}

My approach to solve the issue:

MainView.swift

import UIKit

class MainView: UIView {

    override init(frame: CGRect) {
        super.init(frame: frame)
        setupUI()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

    private func setupUI() {
        backgroundColor = UIColor.lightGray
        setupSubViews()
        setupAutoLayout()
    }

    // MARK: Initialize UI Elements
    private let searchBar: UISearchBar = {
        let searchBar = UISearchBar()
        searchBar.isTranslucent = false
        searchBar.barTintColor = ColorPalette.LuminousDay.white
        searchBar.layoutIfNeeded()
        return searchBar
    }()

    private let searchImageView: UIImageView = {
        let image = UIImage(named: "Search")
        let imageView = UIImageView(image: image)
        imageView.contentMode = .scaleAspectFit
        return imageView
    }()

    private lazy var searchBarTextField: UITextField = { [unowned self] in
        let textField = self.searchBar.value(forKey: "searchBarTextField") as! UITextField
        textField.font = FontBook.SourceSansPro.Weight.semiBold.setFont(size: 24)
        textField.textColor = ColorPalette.LuminousDay.charm
        textField.tintColor = ColorPalette.LuminousDay.charm
        textField.clearButtonMode = .never
        textField.leftViewMode = .never
        textField.leftView = nil
        textField.rightViewMode = .always
        textField.rightView = self.searchImageView
        return textField
    }()

    private func setupSubViews() {
        addSubview(searchBar)
        searchBar.addSubview(searchBarTextField)
        searchBarTextField.addSubview(searchImageView)
    }

    private func setupAutoLayout() {
        searchBar.anchor(top: safeAreaLayoutGuide.topAnchor, bottom: nil,
                         leading: safeAreaLayoutGuide.leadingAnchor, trailing: safeAreaLayoutGuide.trailingAnchor,
                         centerX: nil, centerY: nil,
                         centerXconstant: nil, centerYconstant: nil,
                         size: CGSize.zero, padding: UIEdgeInsets(top: 50, left: 0, bottom: 0, right: 0))

        searchImageView.setSize(size: CGSize(width: 16, height: 16))
    }
}

MainController.swift

import UIKit

class MainController: UIViewController {

    override func loadView() {
        view = MainView()
    }

    override func viewDidLoad() {
        super.viewDidLoad()

    }
}