CODE EXAMPLE FOR SWIFT

Button on right side/view of UITextField

let button = UIButton(type: .custom)
button.setImage(UIImage(named: "send.png"), for: .normal)
button.imageEdgeInsets = UIEdgeInsetsMake(0, -16, 0, 0)
button.frame = CGRect(x: CGFloat(txt.frame.size.width - 25), y: CGFloat(5), width: CGFloat(25), height: CGFloat(25))
button.addTarget(self, action: #selector(self.refresh), for: .touchUpInside)
textField.rightView = button
textField.rightViewMode = .always