Load progress indicator

SBrowser/Browser View/BrowserViewController.swift

@@ -19,6 +19,8 @@ class BrowserViewController: UIViewController,
     private var blockedScriptOrigins = Set<String>()
     override var canBecomeFirstResponder: Bool { true }
     
+    private var loadingObservation: NSKeyValueObservation?
+    
     init() {
         super.init(nibName: nil, bundle: nil)
     }
@@ -53,6 +55,11 @@ class BrowserViewController: UIViewController,
         // TextField delegate
         toolbarController.urlBar.textField.delegate = self
         
+        // Load progress
+        loadingObservation = webView.observe(\.estimatedProgress) { (webView, observedChange) in
+            self.toolbarController.urlBar.loadProgress = .loading(progress: webView.estimatedProgress)
+        }
+        
         self.view = browserView
     }
     
@@ -94,6 +101,10 @@ class BrowserViewController: UIViewController,
         }
     }
     
+    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
+        toolbarController.urlBar.loadProgress = .complete
+    }
+    
     // MARK: UITextField Delegate
     
     func textFieldShouldReturn(_ textField: UITextField) -> Bool {

SBrowser/Browser View/URLBar.swift

@@ -12,7 +12,17 @@ class URLBar: UIView
     let textField = UITextField(frame: .zero)
     let refreshButton = UIButton(frame: .zero)
     
+    public enum LoadProgress {
+        case complete
+        case loading(progress: Double)
+    }
+    
+    public var loadProgress: LoadProgress = .complete {
+        didSet { updateProgressIndicator() }
+    }
+    
     private let backgroundView = UIVisualEffectView(effect: UIBlurEffect(style: .systemThickMaterial))
+    private let progressIndicatorView = ProgressIndicatorView()
     
     convenience init() {
         self.init(frame: .zero)
@@ -26,6 +36,8 @@ class URLBar: UIView
         backgroundView.isUserInteractionEnabled = false
         addSubview(backgroundView)
         
+        backgroundView.contentView.addSubview(progressIndicatorView)
+        
         textField.backgroundColor = .clear
         textField.textContentType = .URL
         textField.keyboardType = .webSearch
@@ -40,19 +52,60 @@ class URLBar: UIView
         addSubview(refreshButton)
     }
     
-    override var intrinsicContentSize: CGSize
-    {
+    private func updateProgressIndicator() {
+        UIView.animate(withDuration: 0.4) {
+            switch self.loadProgress {
+            case .complete:
+                self.progressIndicatorView.progress = 1.0
+                self.progressIndicatorView.alpha = 0.0
+            case .loading(let progress):
+                self.progressIndicatorView.progress = progress
+                self.progressIndicatorView.alpha = 1.0
+            }
+        } completion: { _ in
+            if case LoadProgress.complete = self.loadProgress {
+                // Reset back to zero
+                self.progressIndicatorView.progress = 0.0
+            }
+        }
+    }
+    
+    override var intrinsicContentSize: CGSize {
         let preferredHeight = CGFloat(34)
         return CGSize(width: 1000.0, height: preferredHeight)
     }
     
-    override func layoutSubviews()
-    {
+    override func layoutSubviews() {
         super.layoutSubviews()
         backgroundView.frame = bounds
+        progressIndicatorView.frame = backgroundView.contentView.bounds
         textField.frame = bounds.insetBy(dx: 6.0, dy: 0)
         
         let refreshButtonSize = CGSize(width: textField.frame.height, height: textField.frame.height)
         refreshButton.frame = CGRect(origin: CGPoint(x: bounds.width - refreshButtonSize.width, y: 0), size: refreshButtonSize)
     }
 }
+
+class ProgressIndicatorView: UIView
+{
+    public var progress: Double = 0.0 {
+        didSet { layoutSubviews() }
+    }
+    
+    private let progressFillView = UIView(frame: .zero)
+    
+    convenience init() {
+        self.init(frame: .zero)
+        
+        progressFillView.backgroundColor = .systemBlue
+        progressFillView.alpha = 0.3
+        addSubview(progressFillView)
+    }
+    
+    override func layoutSubviews() {
+        super.layoutSubviews()
+        
+        let width = CGFloat(progress) * bounds.width
+        progressFillView.frame = CGRect(origin: .zero, size: CGSize(width: width, height: bounds.height))
+    }
+}