Swift 3 Initializing buttons - uibutton

Question

Where does one put button initialization code for controls. It won't work in ViewController.swift correct? because I need it to init immediately, not after a button is pressed.
For example I want rounded corners on the buttons.
#IBAction func buttonAdd(_ sender: AnyObject) {
let button = buttonAdd!
button.backgroundColor = UIColor.cyan
// button.backgroundColor = .clear
button.layer.cornerRadius = 15
button.layer.borderWidth = 1
button.layer.borderColor = UIColor.black.cgColor
}
However the this let statement won't work outside of the function either.
Do I need to put init code in a function?
Where would I call the function from?

Answer 1

'buttonAdd' is a function, not a button.
try this code.
if let button = sender as? UIButton
{
button.backgroundColor = UIColor.cyan
// button.backgroundColor = .clear
button.layer.cornerRadius = 15
button.layer.borderWidth = 1
button.layer.borderColor = UIColor.black.cgColor
}
So, you want to init the button with roundedCorner and border.
There's a 'viewDidLoad' function that called only once in view controller's life cycle.
If you want to do something only once, do it in 'viewDidLoad' function.
override func viewDidLoad()
{
super.viewDidLoad()
let btn = UIButton(type: .custom)
btn.frame = .init(x: 100, y: 100, width: 100, height: 30)
btn.setTitle("Hello", for: .normal)
btn.backgroundColor = UIColor.cyan
btn.layer.cornerRadius = 15
btn.layer.borderColor = UIColor.black.cgColor
btn.layer.borderWidth = 1
// you must call this for rounded corner
btn.layer.masksToBounds = true
self.view.addSubview(btn)
}
If you created your button in Interface Builder, You can do it like this.
#IBOutlet weak var btn: UIButton!
override func viewDidLoad()
{
super.viewDidLoad()
btn.layer.cornerRadius = 15
btn.layer.borderColor = UIColor.black.cgColor
btn.layer.borderWidth = 1
// you must call this for rounded corner
btn.layer.masksToBounds = true
}

Answer 2

I found the answer to my question...You would put button init code in ViewController.Swift...in the following function created automatically by the View Controller and you must add button Outlet in addition to button Action.
override func viewDidLoad() {
super.viewDidLoad()
let button = buttonAdd!
button.backgroundColor = UIColor.cyan
// button.backgroundColor = .clear
button.layer.cornerRadius = 10
button.layer.borderWidth = 1
button.layer.borderColor = UIColor.black.cgColor