samples issue-70: added internal delegation for TabBar to be used by TabsController

Material.xcodeproj/project.pbxproj

@@ -358,7 +358,7 @@
 		96BCB7971CB40DC500C806FE /* NavigationDrawerController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = NavigationDrawerController.swift; sourceTree = "<group>"; };
 		96BCB7981CB40DC500C806FE /* Bar.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Bar.swift; sourceTree = "<group>"; };
 		96BCB7991CB40DC500C806FE /* TransitionController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TransitionController.swift; sourceTree = "<group>"; };
-		96BCB79A1CB40DC500C806FE /* TabBar.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TabBar.swift; sourceTree = "<group>"; };
+		96BCB79A1CB40DC500C806FE /* TabBar.swift */ = {isa = PBXFileReference; fileEncoding = 4; indentWidth = 4; lastKnownFileType = sourcecode.swift; path = TabBar.swift; sourceTree = "<group>"; tabWidth = 4; };
 		96BCB79C1CB40DC500C806FE /* TextField.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TextField.swift; sourceTree = "<group>"; };
 		96BCB79D1CB40DC500C806FE /* TextStorage.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TextStorage.swift; sourceTree = "<group>"; };
 		96BCB79E1CB40DC500C806FE /* TextView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TextView.swift; sourceTree = "<group>"; };

Sources/iOS/TabBar.swift

@@ -74,6 +74,18 @@ public protocol TabBarDelegate {
     optional func tabBar(tabBar: TabBar, didSelect tabItem: TabItem)
 }
 
+@objc(_TabBarDelegate)
+internal protocol _TabBarDelegate {
+    /**
+     A delegation method that is executed when the tabItem will trigger the
+     animation to the next tab.
+     - Parameter tabBar: A TabBar.
+     - Parameter tabItem: A TabItem.
+     */
+    @objc
+    optional func _tabBar(tabBar: TabBar, willSelect tabItem: TabItem)
+}
+
 @objc(TabBarStyle)
 public enum TabBarStyle: Int {
     case auto
@@ -124,6 +136,7 @@ open class TabBar: Bar {
     
     /// A delegation reference.
     open weak var delegate: TabBarDelegate?
+    internal weak var _delegate: _TabBarDelegate?
     
     /// The currently selected tabItem.
     open internal(set) var selectedTabItem: TabItem?
@@ -402,6 +415,7 @@ fileprivate extension TabBar {
      */
     func animate(to tabItem: TabItem, isTriggeredByUserInteraction: Bool, completion: ((TabItem) -> Void)? = nil) {
         if isTriggeredByUserInteraction {
+            _delegate?._tabBar?(tabBar: self, willSelect: tabItem)
             delegate?.tabBar?(tabBar: self, willSelect: tabItem)
         }
         

Sources/iOS/TabsController.swift

@@ -284,6 +284,7 @@ fileprivate extension TabsController {
     /// Prepares the TabBar.
     func prepareTabBar() {
         tabBar.lineAlignment = .bottom == tabBarAlignment ? .top : .bottom
+        tabBar._delegate = self
         tabBar.delegate = self
         view.addSubview(tabBar)
     }
@@ -378,9 +379,9 @@ extension TabsController {
     }
 }
 
-extension TabsController: TabBarDelegate {
+extension TabsController: _TabBarDelegate {
     @objc
-    open func tabBar(tabBar: TabBar, willSelect tabItem: TabItem) {
+    func _tabBar(tabBar: TabBar, willSelect tabItem: TabItem) {
         guard !(false == tabBar.delegate?.tabBar?(tabBar: tabBar, shouldSelect: tabItem)) else {
             return
         }
@@ -406,3 +407,5 @@ extension TabsController: TabBarDelegate {
         }
     }
 }
+
+extension TabsController: TabBarDelegate {}