Fix nav bar and colors in main_0.2 branch (#798)

* Fix nav bar and colors in main_0.1 branch (#795)

* Update `MSFNavigationBar` for iOS 15 (#747)

* Update `MSFNavigationBar` for iOS 15

* Fix appearance of test slideover drawer

* Fix build with `#available` tags, and root view

* Adding part of #747 for `changeStyleContinuously`

ios/FluentUI.Demo/FluentUI.Demo/DemoListViewController.swift

@@ -22,6 +22,12 @@ class DemoListViewController: UITableViewController {
         window.rootViewController = navigationController
         window.makeKeyAndVisible()
 
+        if #available(iOS 13, *) {
+            let standardAppearance = navigationController.navigationBar.standardAppearance
+            standardAppearance.backgroundColor = Colors.NavigationBar.background
+            navigationController.navigationBar.scrollEdgeAppearance = standardAppearance
+        }
+
         if let viewController = viewController {
             navigationController.pushViewController(viewController, animated: false)
         }

ios/FluentUI.Demo/FluentUI.Demo/Demos/NavigationControllerDemoController.swift

@@ -180,6 +180,7 @@ class NavigationControllerDemoController: DemoController {
             }
 
             navigationItem.navigationBarStyle = newStyle
+            self.setNeedsStatusBarAppearanceUpdate()
             self.changeStyleContinuously(in: navigationItem)
         }
     }
@@ -451,6 +452,7 @@ class RootViewController: UIViewController, UITableViewDataSource, UITableViewDe
 
     @objc private func showModalView() {
         let modalNavigationController = UINavigationController(rootViewController: ModalViewController(style: .grouped))
+        modalNavigationController.navigationBar.isTranslucent = true
         present(modalNavigationController, animated: true)
     }
 

ios/FluentUI/Navigation/NavigationBar.swift

@@ -324,11 +324,15 @@ open class NavigationBar: UINavigationBar {
         rightBarButtonItemsStackView.setContentHuggingPriority(.defaultHigh, for: .horizontal)
         rightBarButtonItemsStackView.setContentCompressionResistancePriority(.defaultHigh, for: .horizontal)
 
-        updateViewsForLargeTitlePresentation(for: topItem)
-        updateColors(for: topItem)
-
         isTranslucent = false
 
+        // Cache the system shadow color
+        if #available(iOS 13, *) {
+            systemShadowColor = standardAppearance.shadowColor
+        }
+
+        updateColors(for: topItem)
+        updateViewsForLargeTitlePresentation(for: topItem)
         updateAccessibilityElements()
     }
 
@@ -490,7 +494,12 @@ open class NavigationBar: UINavigationBar {
                 titleView.style = .dark
             }
 
-            barTintColor = color
+            if #available(iOS 13, *) {
+                standardAppearance.backgroundColor = color
+                scrollEdgeAppearance = standardAppearance
+            } else {
+                barTintColor = color
+            }
             backgroundView.backgroundColor = color
             tintColor = style.tintColor
             if var titleTextAttributes = titleTextAttributes {
@@ -668,6 +677,9 @@ open class NavigationBar: UINavigationBar {
 
     // MARK: Large/Normal Title handling
 
+    /// Cache for the system shadow color, since the default value is private.
+    private var systemShadowColor: UIColor?
+
     private func updateViewsForLargeTitlePresentation(for navigationItem: UINavigationItem?) {
         // UIView.isHidden has a bug where a series of repeated calls with the same parameter can "glitch" the view into a permanent shown/hidden state
         // i.e. repeatedly trying to hide a UIView that is already in the hidden state
@@ -695,12 +707,25 @@ open class NavigationBar: UINavigationBar {
 
     private func updateShadow(for navigationItem: UINavigationItem?) {
         if needsShadow(for: navigationItem) {
-            shadowImage = nil
-            // Forcing layout to update size of shadow image view otherwise it stays with 0 height
-            setNeedsLayout()
-            subviews.forEach { $0.setNeedsLayout() }
+            if #available(iOS 13, *) {
+                standardAppearance.shadowColor = systemShadowColor
+            } else {
+                shadowImage = nil
+                // Forcing layout to update size of shadow image view otherwise it stays with 0 height
+                setNeedsLayout()
+                subviews.forEach { $0.setNeedsLayout() }
+            }
         } else {
-            shadowImage = UIImage()
+            if #available(iOS 13, *) {
+                standardAppearance.shadowColor = nil
+            } else {
+                shadowImage = UIImage()
+            }
+        }
+
+        if #available(iOS 13, *) {
+            // Update the scroll edge shadow to match standard
+            scrollEdgeAppearance = standardAppearance
         }
     }