Loading an "overlay" when running long tasks in iOS

Solution 1:

The above answers add a loading view but it doesn't block click events on the screen also it does not provides overlay for rest of screen. You can achieve it as follows:

let alert = UIAlertController(title: nil, message: "Please wait...", preferredStyle: .Alert)

alert.view.tintColor = UIColor.blackColor()
let loadingIndicator: UIActivityIndicatorView = UIActivityIndicatorView(frame: CGRectMake(10, 5, 50, 50)) as UIActivityIndicatorView
loadingIndicator.hidesWhenStopped = true
loadingIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.Gray
loadingIndicator.startAnimating();

alert.view.addSubview(loadingIndicator)
presentViewController(alert, animated: true, completion: nil)

Swift 3.0

let alert = UIAlertController(title: nil, message: "Please wait...", preferredStyle: .alert)

let loadingIndicator = UIActivityIndicatorView(frame: CGRect(x: 10, y: 5, width: 50, height: 50))
loadingIndicator.hidesWhenStopped = true
loadingIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.gray
loadingIndicator.startAnimating();

alert.view.addSubview(loadingIndicator)
present(alert, animated: true, completion: nil)

Swift 4.0 and newer

let alert = UIAlertController(title: nil, message: "Please wait...", preferredStyle: .alert)

let loadingIndicator = UIActivityIndicatorView(frame: CGRect(x: 10, y: 5, width: 50, height: 50))
loadingIndicator.hidesWhenStopped = true
loadingIndicator.style = UIActivityIndicatorView.Style.gray
loadingIndicator.startAnimating();

alert.view.addSubview(loadingIndicator)
present(alert, animated: true, completion: nil)

and you can hide it as follows:

dismiss(animated: false, completion: nil)

It will be shown as follows:

Solution 2:

Just create yourself an overlay view, which you add to your parent view and remove it once your task is done, e.g. to add it:

var overlay : UIView? // This should be a class variable

[ ... ]

overlay = UIView(frame: view.frame)
overlay!.backgroundColor = UIColor.blackColor()
overlay!.alpha = 0.8

view.addSubview(overlay!)

For removal:

overlay?.removeFromSuperview()

Solution 3:

Blur background + Activity Indicator, Swift 5 example

extension UIView {
    func showBlurLoader() {
        let blurLoader = BlurLoader(frame: frame)
        self.addSubview(blurLoader)
    }

    func removeBluerLoader() {
        if let blurLoader = subviews.first(where: { $0 is BlurLoader }) {
            blurLoader.removeFromSuperview()
        }
    }
}


class BlurLoader: UIView {

    var blurEffectView: UIVisualEffectView?

    override init(frame: CGRect) {
        let blurEffect = UIBlurEffect(style: .dark)
        let blurEffectView = UIVisualEffectView(effect: blurEffect)
        blurEffectView.frame = frame
        blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        self.blurEffectView = blurEffectView
        super.init(frame: frame)
        addSubview(blurEffectView)
        addLoader()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    private func addLoader() {
        guard let blurEffectView = blurEffectView else { return }
        let activityIndicator = UIActivityIndicatorView(style: .whiteLarge)
        activityIndicator.frame = CGRect(x: 0, y: 0, width: 50, height: 50)
        blurEffectView.contentView.addSubview(activityIndicator)
        activityIndicator.center = blurEffectView.contentView.center
        activityIndicator.startAnimating()
    }
}