Merge pull request #920 from markst/issue/919

Tab bar controller dynamically adds & removes child view controllers

Sources/iOS/TabsController.swift

@@ -197,13 +197,15 @@ fileprivate extension TabsController {
             return
         }
         
+        let fvcIndex = viewControllers.index(of: fvc)
+        let tvcIndex = viewControllers.index(of: viewController)
+        
         let tvc = viewController
+        tvc.beginAppearanceTransition(true, animated: true)
+        prepareViewController(at: tvcIndex!)
         tvc.view.isHidden = false
         tvc.view.frame = container.bounds
         
-        let fvcIndex = viewControllers.index(of: fvc)
-        let tvcIndex = viewControllers.index(of: viewController)
-        
         var isAuto = false
         
         switch tvc.motionModalTransitionType {
@@ -229,6 +231,9 @@ fileprivate extension TabsController {
             
             s.rootViewController = tvc
             s.view.isUserInteractionEnabled = true
+            tvc.endAppearanceTransition()
+            
+            s.removeViewController(viewController: fvc)
             
             completion?(isFinished)
             
@@ -249,15 +254,6 @@ internal extension TabsController {
 fileprivate extension TabsController {
     /// Prepares all the view controllers.
     func prepareViewControllers() {
-        for i in 0..<viewControllers.count {
-            guard i != selectedIndex else {
-                continue
-            }
-            
-            viewControllers[i].view.isHidden = true
-            prepareViewController(at: i)
-        }
-        
         prepareViewController(at: selectedIndex)
         prepareRootViewController()
     }