pr-938: An expansion on this PR to fix the lifecycle issues with transitions.

CHANGELOG.md

+## 2.12.7
+
+* [pr-938](https://github.com/CosmicMind/Material/pull/938): An expansion on this PR to fix the lifecycle issues with transitions.
+
 ## 2.12.6
 
 * Fixed issue where TabBar.lineColor was incorrectly being updated.

Sources/iOS/ChipBarController.swift

@@ -108,9 +108,11 @@ fileprivate extension ChipBarController {
             case .top:
                 container.frame.origin.y = p
                 container.frame.size.height = y
+                
             case .bottom:
                 container.frame.origin.y = 0
                 container.frame.size.height = y
+                
             case .hidden:
                 container.frame.origin.y = 0
                 container.frame.size.height = view.bounds.height
@@ -131,9 +133,11 @@ fileprivate extension ChipBarController {
         case .top:
             chipBar.isHidden = false
             chipBar.frame.origin.y = 0
+            
         case .bottom:
             chipBar.isHidden = false
             chipBar.frame.origin.y = view.bounds.height - chipBar.bounds.height
+        
         case .hidden:
             chipBar.isHidden = true
         }

Sources/iOS/SearchBarController.swift

@@ -96,6 +96,7 @@ fileprivate extension SearchBarController {
             case .top:
                 container.frame.origin.y = q + p
                 container.frame.size.height = h
+                
             case .bottom:
                 container.frame.origin.y = q
                 container.frame.size.height = h

Sources/iOS/StatusBarController.swift

@@ -99,6 +99,7 @@ open class StatusBarController: TransitionController {
             let h = statusBar.bounds.height
             container.frame.origin.y = h
             container.frame.size.height = view.bounds.height - h
+            
         case .full:
             container.frame = view.bounds
         }

Sources/iOS/TabsController.swift

@@ -175,9 +175,9 @@ open class TabsController: TransitionController {
         view.backgroundColor = .white
         view.contentScaleFactor = Screen.scale
         
-        prepareSelectedIndexViewController()
         prepareTabBar()
         prepareTabItems()
+        prepareSelectedIndexViewController()
     }
     
     open override func transition(to viewController: UIViewController, completion: ((Bool) -> Void)?) {
@@ -193,53 +193,40 @@ fileprivate extension TabsController {
      - Parameter completion: An optional completion block.
      */
     func transition(to viewController: UIViewController, isTriggeredByUserInteraction: Bool, completion: ((Bool) -> Void)?) {
-        guard let fvc = rootViewController else {
-            return
-        }
-        
-        guard let fvcIndex = viewControllers.index(of: fvc) else {
+        guard let fvcIndex = viewControllers.index(of: rootViewController) else {
             return
         }
         
-        let tvc = viewController
-        
-        guard let tvcIndex = viewControllers.index(of: tvc) else {
+        guard let tvcIndex = viewControllers.index(of: viewController) else {
             return
         }
         
         var isAuto = false
         
-        switch tvc.motionModalTransitionType {
+        switch viewController.motionModalTransitionType {
         case .auto:
             isAuto = true
             viewController.motionModalTransitionType = fvcIndex < tvcIndex ? .slide(direction: .left) : .slide(direction: .right)
         default:break
         }
         
-        prepare(viewController: tvc, in: container)
-        
         if isTriggeredByUserInteraction {
             delegate?.tabsController?(tabsController: self, willSelect: viewController)
         }
         
-        view.isUserInteractionEnabled = false
-        
-        Motion.shared.transition(from: fvc, to: viewController, in: container) { [weak self, tvc = tvc, isAuto = isAuto, completion = completion] (isFinished) in
+        super.transition(to: viewController) { [weak self, isAuto = isAuto, viewController = viewController, completion = completion] (isFinished) in
             guard let s = self else {
                 return
             }
 
             if isAuto {
-                tvc.motionModalTransitionType = .auto
+                viewController.motionModalTransitionType = .auto
             }
 
-            s.rootViewController = tvc
-            s.view.isUserInteractionEnabled = true
-                        
             completion?(isFinished)
 
             if isTriggeredByUserInteraction {
-                s.delegate?.tabsController?(tabsController: s, didSelect: tvc)
+                s.delegate?.tabsController?(tabsController: s, didSelect: viewController)
             }
         }
     }

Sources/iOS/ToolbarController.swift

@@ -97,6 +97,7 @@ fileprivate extension ToolbarController {
             case .top:
                 container.frame.origin.y = q + p
                 container.frame.size.height = h
+                
             case .bottom:
                 container.frame.origin.y = q
                 container.frame.size.height = h

Sources/iOS/TransitionController.swift

@@ -58,18 +58,25 @@ open class TransitionController: UIViewController {
      */
     open internal(set) var rootViewController: UIViewController! {
         willSet {
-            if let v = rootViewController {
-                removeViewController(viewController: v)
+            guard newValue != rootViewController else {
+                return
+            }
+            
+            guard let v = rootViewController else {
+                return
             }
+            
+            removeViewController(viewController: v)
         }
         didSet {
+            guard oldValue != rootViewController else {
+                return
+            }
+            
             prepare(viewController: rootViewController, in: container)
         }
     }
     
-    /// The transition type used during a transition.
-    open var motionTransitionType = MotionTransitionType.fade
-    
     /**
      An initializer that initializes the object with a NSCoder object.
      - Parameter aDecoder: A NSCoder instance.
@@ -119,23 +126,15 @@ open class TransitionController: UIViewController {
      to the toViewController has completed.
      */
     open func transition(to viewController: UIViewController, completion: ((Bool) -> Void)? = nil) {
-        guard let fvc = rootViewController else {
-            return
-        }
-        
-        let tvc = viewController
-        
-        tvc.view.isHidden = false
-        tvc.view.frame = container.bounds
-        tvc.motionModalTransitionType = motionTransitionType
+        prepare(viewController: viewController, in: container)
         
         view.isUserInteractionEnabled = false
-        Motion.shared.transition(from: fvc, to: tvc, in: container) { [weak self, tvc = tvc, completion = completion] (isFinished) in
+        Motion.shared.transition(from: rootViewController, to: viewController, in: container) { [weak self, viewController = viewController, completion = completion] (isFinished) in
             guard let s = self else {
                 return
             }
             
-            s.rootViewController = tvc
+            s.rootViewController = viewController
             s.view.isUserInteractionEnabled = true
             completion?(isFinished)
         }
@@ -161,6 +160,7 @@ open class TransitionController: UIViewController {
         view.contentScaleFactor = Screen.scale
         
         prepareContainer()
+        prepare(viewController: rootViewController, in: container)
     }
 }