Loading an “overlay” when running long tasks in iOS

Question

What is example for loading overlay in Swift IOS application when do a long tasks. Example for loading data from remote server. I googled but not found any answer.

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Answer 1

Swift 3.

I used @Lucho's code in his answer below and I changed the overlay background color to clear and added a spinner color.

public class LoadingOverlay {

    var overlayView : UIView!
    var activityIndicator : UIActivityIndicatorView!

    class var shared: LoadingOverlay {
        struct Static {
            static let instance: LoadingOverlay = LoadingOverlay()
        }
        return Static.instance
    }

    init(){
        self.overlayView = UIView()
        self.activityIndicator = UIActivityIndicatorView()

        overlayView.frame = CGRect(0, 0, 80, 80)
        overlayView.backgroundColor = .clear
        overlayView.clipsToBounds = true
        overlayView.layer.cornerRadius = 10
        overlayView.layer.zPosition = 1

        activityIndicator.frame = CGRect(0, 0, 40, 40)
        activityIndicator.center = CGPoint(overlayView.bounds.width / 2, overlayView.bounds.height / 2)
        activityIndicator.activityIndicatorViewStyle = .whiteLarge
        activityIndicator.color = .gray
        overlayView.addSubview(activityIndicator)
    }

    public func showOverlay(view: UIView) {
        overlayView.center = view.center
        view.addSubview(overlayView)
        activityIndicator.startAnimating()
    }

    public func hideOverlayView() {
        activityIndicator.stopAnimating()
        overlayView.removeFromSuperview()
    }
}