Adding UIBarButtonItem to UIToolbar with left/right alignment

The code below shows how to add UIBarButtonItems to a UIToolbar without a UINavigationBar.

The UIBarButtonItems on UIBarButtonItem may be aligned to the left or to the right. 
The code is written in Swift 2.2 with Xcode 7.3.

Modify ViewController.swift as:

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {

        super.viewDidLoad()

        

        view.backgroundColor = UIColor.lightGrayColor()

        

        //Toolbar 1

        let toolbar1 = UIToolbar()

        toolbar1.sizeToFit()

        toolbar1.center = CGPointMake(view.frame.width/2, 100)

        toolbar1.backgroundColor = UIColor.orangeColor()

        

        //Aligh Left

        let cancel = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Cancel, target: self, action: nil)

        toolbar1.items = [cancel]

        

        //Toolbar 2

        let toolbar2 = UIToolbar()

        toolbar2.sizeToFit()

        toolbar2.center = CGPointMake(view.frame.width/2, 200)

        toolbar2.backgroundColor = UIColor.blueColor()

        

        //Aligh Right

        let flexible = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FlexibleSpace, target: self, action: nil)

        let search = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Search, target: self, action: nil)

        toolbar2.items = [flexible, search]

        

        //Toolbar 3

        let toolbar3 = UIToolbar()

        toolbar3.sizeToFit()

        toolbar3.center = CGPointMake(view.frame.width/2, 300)

        toolbar3.backgroundColor = UIColor.greenColor()

        

        //Alight Left and Right

        let stop = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Stop, target: self, action: nil)

        let add = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Add, target: self, action: nil)

        toolbar3.items = [stop, flexible, add]

        

        view.addSubview(toolbar1)

        view.addSubview(toolbar2)

        view.addSubview(toolbar3)

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

    }

}

Result:

Related Information:

UIBarButtonItem types and UIToolbar color settings