WebKit Observer: Page Load Progress

ProgressObserver.swift

var webViewProgressObserver: NSKeyValueObservation?

@IBOutlet var progressBar: UIProgressView!          // iOS Progress Bar
@IBOutlet var progressBar: NSProgressIndicator!     // macOS Progress Spinner

override func viewDidLoad() {
    super.viewDidLoad()
    
    webViewProgressObserver = webView.observe(\.estimatedProgress, options: .new) { [weak self] webView, change in
        self?.progressDidChange(progress: change.newValue ?? 1.0)
    }
}

func progressDidChange(progress: Double) {
    let value = Float(progress)             // Set value as Float for Progress Indicator
    if value < 1 {                          // While page is loading:
        progressBar.isHidden = false        // Show progress bar
        progressBar.progress = value        // Set value of progress indicator
    } else {                                // When page is done loading:
        progressBar.isHidden = true         // Hide progress bar
    }
    print("Loading: \(value)")              // Print page load progress to console
}