Adding Navigation Bar programmatically iOS

-(void)ViewDidLoad
{
 UINavigationBar* navbar = [[UINavigationBar alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 50)];

UINavigationItem* navItem = [[UINavigationItem alloc] initWithTitle:@"karthik"];
// [navbar setBarTintColor:[UIColor lightGrayColor]];
UIBarButtonItem* cancelBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCancel target:self action:@selector(onTapCancel:)];
navItem.leftBarButtonItem = cancelBtn;

UIBarButtonItem* doneBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(onTapDone:)];
navItem.rightBarButtonItem = doneBtn;

[navbar setItems:@[navItem]];
[self.view addSubview:navbar];
}


-(void)onTapDone:(UIBarButtonItem*)item{

}

-(void)onTapCancel:(UIBarButtonItem*)item{

}

Swift3

let navigationBar = UINavigationBar(frame: CGRect(x: 0, y: 0, width: view.frame.size.width, height:44)) // Offset by 20 pixels vertically to take the status bar into account

    navigationBar.backgroundColor = UIColor.white


    // Create a navigation item with a title
    let navigationItem = UINavigationItem()
    navigationItem.title = "Title"

    // Create left and right button for navigation item
     let leftButton =  UIBarButtonItem(title: "Save", style:   .plain, target: self, action: #selector(ViewController.btn_clicked(_:)))

    let rightButton = UIBarButtonItem(title: "Right", style: .plain, target: self, action: nil)

    // Create two buttons for the navigation item
    navigationItem.leftBarButtonItem = leftButton
    navigationItem.rightBarButtonItem = rightButton

    // Assign the navigation item to the navigation bar
    navigationBar.items = [navigationItem]

    // Make the navigation bar a subview of the current view controller
    self.view.addSubview(navigationBar)




func btn_clicked(_ sender: UIBarButtonItem) {
    // Do something
}

Swift

 // Create the navigation bar
    let navigationBar = UINavigationBar(frame: CGRectMake(0, 0, self.view.frame.size.width, 44)) // Offset by 20 pixels vertically to take the status bar into account

    navigationBar.backgroundColor = UIColor.whiteColor()
    navigationBar.delegate = self;

    // Create a navigation item with a title
    let navigationItem = UINavigationItem()
    navigationItem.title = "Title"

    // Create left and right button for navigation item
    let leftButton =  UIBarButtonItem(title: "Save", style:   UIBarButtonItemStyle.Plain, target: self, action: "btn_clicked:")
    let rightButton = UIBarButtonItem(title: "Right", style: UIBarButtonItemStyle.Plain, target: self, action: nil)

    // Create two buttons for the navigation item
    navigationItem.leftBarButtonItem = leftButton
    navigationItem.rightBarButtonItem = rightButton

    // Assign the navigation item to the navigation bar
    navigationBar.items = [navigationItem]

    // Make the navigation bar a subview of the current view controller
    self.view.addSubview(navigationBar)


  func btn_clicked(sender: UIBarButtonItem) {
  // Do something
 }