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

Updated @sonrobby answer, added a background view and orientation handling via resizing mask... this can be used for simple stuffs

public class LoadingOverlay{

    var overlayView = UIView()
    var activityIndicator = UIActivityIndicatorView()
    var bgView = UIView()

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

    public func showOverlay(view: UIView) {

        bgView.frame = view.frame
        bgView.backgroundColor = UIColor.gray
        bgView.addSubview(overlayView)
        bgView.autoresizingMask = [.flexibleLeftMargin,.flexibleTopMargin,.flexibleRightMargin,.flexibleBottomMargin,.flexibleHeight, .flexibleWidth]
        overlayView.frame = CGRect(x: 0, y: 0, width: 80, height: 80)
        overlayView.center = view.center
        overlayView.autoresizingMask = [.flexibleLeftMargin,.flexibleTopMargin,.flexibleRightMargin,.flexibleBottomMargin]
        overlayView.backgroundColor = UIColor.black
        overlayView.clipsToBounds = true
        overlayView.layer.cornerRadius = 10

        activityIndicator.frame = CGRect(x: 0, y: 0, width: 40, height: 40)
        activityIndicator.activityIndicatorViewStyle = .whiteLarge
        activityIndicator.center = CGPoint(x: overlayView.bounds.width / 2, y: overlayView.bounds.height / 2)

        overlayView.addSubview(activityIndicator)
        view.addSubview(bgView)
        self.activityIndicator.startAnimating()

    }

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

if you add it to keywindow, it can then go over your nav and tab bars also... something like this

LoadingOverlay.shared.showOverlay(view: UIApplication.shared.keyWindow!)