Swift extension example

Question

I was originally wanting to know how to make something like this

UIColor.myCustomGreen

so that I could define my own colors and use them th

Answer 1

One of the best example of extension and convenience initializer :

 extension UIActivityIndicatorView {
    convenience init(activityIndicatorStyle: UIActivityIndicatorViewStyle, color: UIColor, placeInTheCenterOf parentView: UIView) {
    self.init(activityIndicatorStyle: activityIndicatorStyle)
    center = parentView.center
    self.color = color
    parentView.addSubview(self)
  }
}

You can use it in following ways :

1. Initialize activityIndicator

   let activityIndicator = UIActivityIndicatorView(activityIndicatorStyle: .whiteLarge, color: .gray,  placeInTheCenterOf: view)
   

2. Start animating activity indicator

   activityIndicator.startAnimating()
   

3. Stop animating activity indicator

   activityIndicator.stopAnimating()