iOS + Swift: Display activity indicator overlay - UIViewController extension

ActivityIndicatorOverlay.swift

import UIKit

fileprivate let overlayViewTag: Int = 999
fileprivate let activityIndicatorViewTag: Int = 1000

// Public interface
extension UIView {
    func displayAnimatedActivityIndicatorView() {
        setActivityIndicatorView()
    }

    func hideAnimatedActivityIndicatorView() {
        removeActivityIndicatorView()
    }
}

extension UIViewController {
    private var overlayContainerView: UIView {
        if let navigationView: UIView = navigationController?.view {
            return navigationView
        }
        return view
    }

    func displayAnimatedActivityIndicatorView() {
        overlayContainerView.displayAnimatedActivityIndicatorView()
    }

    func hideAnimatedActivityIndicatorView() {
        overlayContainerView.hideAnimatedActivityIndicatorView()
    }
}

// Private interface
extension UIView {
    private var activityIndicatorView: UIActivityIndicatorView {
        let view: UIActivityIndicatorView = UIActivityIndicatorView(style: .large)
        view.translatesAutoresizingMaskIntoConstraints = false
        view.tag = activityIndicatorViewTag
        return view
    }

    private var overlayView: UIView {
        let view: UIView = UIView()
        view.translatesAutoresizingMaskIntoConstraints = false
        view.backgroundColor = .black
        view.alpha = 0.5
        view.tag = overlayViewTag
        return view
    }

    private func setActivityIndicatorView() {
        guard !isDisplayingActivityIndicatorOverlay() else { return }
        let overlayView: UIView = self.overlayView
        let activityIndicatorView: UIActivityIndicatorView = self.activityIndicatorView

        //add subviews
        overlayView.addSubview(activityIndicatorView)
        addSubview(overlayView)

        //add overlay constraints
        overlayView.heightAnchor.constraint(equalTo: heightAnchor).isActive = true
        overlayView.widthAnchor.constraint(equalTo: widthAnchor).isActive = true

        //add indicator constraints
        activityIndicatorView.centerXAnchor.constraint(equalTo: overlayView.centerXAnchor).isActive = true
        activityIndicatorView.centerYAnchor.constraint(equalTo: overlayView.centerYAnchor).isActive = true

        //animate indicator
        activityIndicatorView.startAnimating()
    }

    private func removeActivityIndicatorView() {
        guard let overlayView: UIView = getOverlayView(), let activityIndicator: UIActivityIndicatorView = getActivityIndicatorView() else {
            return
        }
        UIView.animate(withDuration: 0.2, animations: {
            overlayView.alpha = 0.0
            activityIndicator.stopAnimating()
        }) { _ in
            activityIndicator.removeFromSuperview()
            overlayView.removeFromSuperview()
        }
    }

    private func isDisplayingActivityIndicatorOverlay() -> Bool {
        getActivityIndicatorView() != nil && getOverlayView() != nil
    }

    private func getActivityIndicatorView() -> UIActivityIndicatorView? {
        viewWithTag(activityIndicatorViewTag) as? UIActivityIndicatorView
    }

    private func getOverlayView() -> UIView? {
        viewWithTag(overlayViewTag)
    }
}

Updated the snippet with @acamill's suggested code. Thank you!

Changes:

• Added type annotation
• Separated the display method into display and hide, in order to have single responsibility methods
• Added UIViewController extension to use the overlay to cover the fullscreen without having to write navigationController?.view.displayAnimatedActivityIndicatorView()

Cheers!

…

On Fri, 29 May 2020 at 9:26 PM, Eduard Moya ***@***.***> wrote: ***@***.**** commented on this gist. ------------------------------ Updated the snippet with @acamill's <https://gist.github.com/acamill> suggested code. Thank you! Changes: - Added type annotation - Separated the display method into display and hide, in order to have single responsibility methods - Added UIViewController extension to use the overlay to cover the fullscreen without having to write navigationController?.view.displayAnimatedActivityIndicatorView() — You are receiving this because you commented. Reply to this email directly, view it on GitHub <https://gist.github.com/e4bed05b4c6653ffcd36c0609f27c7c6#gistcomment-3322674>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AJTOZY7BLLMUXOSUJPUXYJDRT6ZZBANCNFSM4JRGSANA> .

How is this applied to a normal swiftUI page. If I want the page to display the loading icon how do I do that?

Import SwiftUI

struct Welcome: View {
  
    var body: some View {
<< DISPLAY LOADING HERE >>
        Text("Hello World")
    }
}

struct Dashboard_Previews: PreviewProvider {
    static var previews: some View {
        Welcome()
    }
    
}

Thanks for sharing!

💁‍♂️

…

On Thu, 6 Aug 2020 at 11:45 AM, ahmdmau ***@***.***> wrote: ***@***.**** commented on this gist. ------------------------------ Thanks for sharing! — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <https://gist.github.com/e4bed05b4c6653ffcd36c0609f27c7c6#gistcomment-3406425>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AJTOZY6GEGBSYFR4MLI2PDDR7IRO5ANCNFSM4JRGSANA> .