UIbutton background colour and button enable/disable - swift3

Question

How can we set a hex value to the background of button value is #88D317? Also, I want to keep the button enabled only if there is text present in textfields, else disabled.
Here is the code I have written:
class ViewControllerDonarLogin: UIViewController, UITextFieldDelegate {
#IBOutlet var btnlogin: UIButton!
#IBOutlet weak var btn: UIButton!
#IBOutlet weak var textfieldpassword: UITextField!
#IBOutlet weak var textfieldusername: UITextField!
var alert : UIAlertController = UIAlertController()
var action : UIAlertAction = UIAlertAction()
override func viewDidLoad() {
super.viewDidLoad()
buttonborder()
btnlogin.backgroundColor = UIColor(red: 136/255, green: 211/255, blue: 23/255, alpha: 0.5)
if textfieldpassword.text == "" && textfieldusername.text == "" {
btnlogin.isEnabled = false
} else {
btnlogin.isEnabled = true
}
// Do any additional setup after loading the view.
}
}

Answer 1

You can use one of the text field's UIControl actions.
In viewDidLoad, add self as a target for editingChanged:
textfieldpassword.addTarget(self, action: #selector(textChanged), for: .editingChanged)
textfieldusername.addTarget(self, action: #selector(textChanged), for: .editingChanged)
Now, add this method:
func textChanged() {
// This will be called every time the text field's text changes
}
Move the original code you wrote in viewDidLoad to the above method.
if textfieldpassword.text == "" || textfieldusername.text == ""
{
btnlogin.isEnabled = false
}
else
{
btnlogin.isEnabled = true
}

Answer 2

What you want to achieve can be done by using text field delegates. You will have to use
func textFieldDidEndEditing(_ textField: UITextField) {
if textfieldpassword.text == "" || textfieldusername.text == "" {
btnlogin.isEnabled = false
} else {
btnlogin.isEnabled = true
}
}
also you will have to disable the button in viewDidLoad:
override func viewDidLoad() {
super.viewDidLoad()
btnlogin.isEnabled = false // as you want button to be disabled at the starting
}