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.

U

Answer 1

Swift 5

class func showUniversalLoadingView(_ show: Bool, loadingText : String = "") {
    let existingView = UIApplication.shared.windows[0].viewWithTag(1200)
    if show {
        if existingView != nil {
            return
        }
        let loadingView = self.makeLoadingView(withFrame: UIScreen.main.bounds, loadingText: loadingText)
        loadingView?.tag = 1200
        UIApplication.shared.windows[0].addSubview(loadingView!)
    } else {
        existingView?.removeFromSuperview()
    }

}



 class func makeLoadingView(withFrame frame: CGRect, loadingText text: String?) -> UIView? {
    let loadingView = UIView(frame: frame)
    loadingView.backgroundColor = UIColor(red: 0, green: 0, blue: 0, alpha: 0.5)
    let activityIndicator = UIActivityIndicatorView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
    //activityIndicator.backgroundColor = UIColor(red:0.16, green:0.17, blue:0.21, alpha:1)
    activityIndicator.layer.cornerRadius = 6
    activityIndicator.center = loadingView.center
    activityIndicator.hidesWhenStopped = true
    activityIndicator.style = .white
    activityIndicator.startAnimating()
    activityIndicator.tag = 100 // 100 for example

    loadingView.addSubview(activityIndicator)
    if !text!.isEmpty {
        let lbl = UILabel(frame: CGRect(x: 0, y: 0, width: 200, height: 30))
        let cpoint = CGPoint(x: activityIndicator.frame.origin.x + activityIndicator.frame.size.width / 2, y: activityIndicator.frame.origin.y + 80)
        lbl.center = cpoint
        lbl.textColor = UIColor.white
        lbl.textAlignment = .center
        lbl.text = text
        lbl.tag = 1234
        loadingView.addSubview(lbl)
    }
    return loadingView
}

Uses

showUniversalLoadingView(true, loadingText: "Downloading Data.......")

showUniversalLoadingView(true)

Remove loader

showUniversalLoadingView(false)

Answer 2

To add on to the answers given, you might run into issues if you are attempting to run the code sometimes. Personally, there was an occasion where showOverlay was not being properly called (because I was trying to segue into a scene, then immediately call this function during viewDidLoad).

If you run into an issue similar to mine, there is one fix to the code and a change in approach I recommend.

FIX: Place both blocks of code as closures to a dispatch_async call, like so:

dispatch_async(dispatch_get_main_queue(),
 { //code });

APPROACH: When calling your code, do a dispatch_after call onto the main queue to delay the call by a few milliseconds.

The reasoning? You're simply asking the UI to do too much during viewDidLoad.

If this appendix to the solution helped, I'd be glad.

-Joel Long

P.S. Solution worked for XCode v6.3.2

Answer 3

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!)

Answer 4

@Ajinkya Patil answer as a reference. Swift 4.0 and newer

This is an Extension Solution to use on all viewController without clashing.

Create a LoadingDialog+ViewContoller.swift

import UIKit

struct ProgressDialog {
    static var alert = UIAlertController()
    static var progressView = UIProgressView()
    static var progressPoint : Float = 0{
        didSet{
            if(progressPoint == 1){
                ProgressDialog.alert.dismiss(animated: true, completion: nil)
            }
        }
    }
}
extension UIViewController{
   func LoadingStart(){
        ProgressDialog.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();

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

  func LoadingStop(){
    ProgressDialog.alert.dismiss(animated: true, completion: nil)
  }
}

call the function inside ViewController anywhere you like. like so:

self.LoadingStart()

and here's how to stop the loading dialog.

self.LoadingStop()

Answer 5

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()
    }
}

Answer 6

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()