Fixed backButton issues with navigation bar show/hide

Sources/iOS/NavigationController.swift

@@ -146,6 +146,22 @@ open class NavigationController: UINavigationController {
     navigationBar.setNeedsLayout()
     navigationBar.setNeedsLayout()
     navigationBar.layoutIfNeeded()
     navigationBar.layoutIfNeeded()
   }
   }
+  
+  /**
+   Sets whether the navigation bar is hidden.
+   - Parameter _ hidden: Specify true to hide the navigation bar or false to show it.
+   - Parameter animated: Specify true if you want to animate the change in visibility or false if you want the navigation bar to appear immediately.
+   */
+  open override func setNavigationBarHidden(_ hidden: Bool, animated: Bool) {
+    super.setNavigationBarHidden(hidden, animated: animated)
+    guard let items = navigationBar.items, items.count > 1 else {
+      return
+    }
+    
+    items.forEach {
+      prepareBackButton(for: $0, in: navigationBar)
+    }
+  }
 }
 }
 
 
 extension NavigationController: UINavigationBarDelegate {
 extension NavigationController: UINavigationBarDelegate {
@@ -158,12 +174,37 @@ extension NavigationController: UINavigationBarDelegate {
    True is yes, false is no.
    True is yes, false is no.
    */
    */
   public func navigationBar(_ navigationBar: UINavigationBar, shouldPush item: UINavigationItem) -> Bool {
   public func navigationBar(_ navigationBar: UINavigationBar, shouldPush item: UINavigationItem) -> Bool {
-    if let v = navigationBar as? NavigationBar {
+    prepareBackButton(for: item, in: navigationBar)
+    return true
+  }
+  
+  public func navigationBar(_ navigationBar: UINavigationBar, didPop item: UINavigationItem) {
+    removeBackButton(from: item)
+  }
+}
+
+internal extension NavigationController {
+  /// Handler for the backbutton.
+  @objc
+  func handle(backButton: UIButton) {
+    popViewController(animated: true)
+  }
+  
+  /**
+   Prepares back button of the navigation item in navigation bar.
+   - Parameter for item: A UINavigationItem.
+   - Parameter in navigationBar: A UINavigationBar.
+   */
+  func prepareBackButton(for item: UINavigationItem, in navigationBar: UINavigationBar) {
+    guard let v = navigationBar as? NavigationBar else {
+      return
+    }
+    
     if nil == item.backButton.image && nil == item.backButton.title {
     if nil == item.backButton.image && nil == item.backButton.title {
       item.backButton.image = v.backButtonImage
       item.backButton.image = v.backButtonImage
     }
     }
     
     
-      if !item.backButton.isHidden {
+    if !item.backButton.isHidden && !item.leftViews.contains(item.backButton) {
       item.leftViews.insert(item.backButton, at: 0)
       item.leftViews.insert(item.backButton, at: 0)
     }
     }
     
     
@@ -175,10 +216,11 @@ extension NavigationController: UINavigationBarDelegate {
     v.layoutNavigationItem(item: item)
     v.layoutNavigationItem(item: item)
   }
   }
   
   
-    return true
-  }
-  
-  public func navigationBar(_ navigationBar: UINavigationBar, didPop item: UINavigationItem) {
+  /**
+   Removes back button of the navigation item.
+   - Parameter from item: A UINavigationItem.
+   */
+  func removeBackButton(from item: UINavigationItem) {
     if let index = item.leftViews.index(of: item.backButton) {
     if let index = item.leftViews.index(of: item.backButton) {
       item.leftViews.remove(at: index)
       item.leftViews.remove(at: index)
     }
     }
@@ -187,14 +229,6 @@ extension NavigationController: UINavigationBarDelegate {
   }
   }
 }
 }
 
 
-internal extension NavigationController {
-  /// Handler for the backbutton.
-  @objc
-  func handle(backButton: UIButton) {
-    popViewController(animated: true)
-  }
-}
-
 extension NavigationController: UIGestureRecognizerDelegate {
 extension NavigationController: UIGestureRecognizerDelegate {
   /**
   /**
    Detects the gesture recognizer being used. This is necessary when using
    Detects the gesture recognizer being used. This is necessary when using