Evenly space UIToolbar buttons in inputAccessoryView - swift

Question

In the following code I have three buttons that show when an inputField is tapped. Right now the buttons show but all of them are shifted to the left and what I would like to do is have them evenly space and keep them like that regardless of what phone size they are viewed on.
How can I evenly space the buttons in a UIToolbar?
CODE:
override func viewDidLoad() {
super.viewDidLoad()
addButtonsToKeyboard()
}
// Reusable Button
func configurButton(button:UIButton) {
button.backgroundColor = UIColor.whiteColor()
button.layer.cornerRadius = 5
button.layer.borderWidth = 1.0
button.layer.borderColor = UIColor.blueColor().CGColor
button.setTitleColor(UIColor.lightGrayColor(), forState: .Normal)
button.setTitleColor(UIColor.blueColor(), forState: .Highlighted)
button.frame = CGRect(x:0, y:0, width:50, height:35)
button.addTarget(self, action: #selector(customKeyPressed), forControlEvents: UIControlEvents.TouchUpInside)
}
func addButtonsToKeyboard(){
// First button
let button1 = UIButton()
button1.setTitle("Btn 1", forState: .Normal)
configureButton(button1)
let barButton1 = UIBarButtonItem()
barButton1.customView = button1
// Second button
let button2 = UIButton()
button2.setTitle("Btn 2", forState: .Normal)
configureButton(button2)
let barButton2 = UIBarButtonItem()
barButton2.customView = button2
// Third button
let button3 = UIButton()
button3.setTitle("Btn 3", forState: .Normal)
configureButton(button3)
let barButton3 = UIBarButtonItem()
barButton3.customView = button3
/**
* UIToolbar.
*/
let toolBar = UIToolbar()
toolBar.tintColor = UIColor.redColor()
toolBar.barTintColor = UIColor.lightGrayColor()
toolBar.items = [barButton1, barButton2, barButton3]
toolBar.sizeToFit()
myInputField.inputAccessoryView = toolBar
}
func customKeyPressed(sender: UIButton){
// do something
}
CURRENT:
AFTER:

Answer 1

Very simple, you just need to add a flexible bar button item between each button. See the following:
let space = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
toolbar.items = [barButton1, space, barButton2, space, barButton3]