Add TitleBar subtitle support on Android

android/app/src/main/java/com/reactnativenavigation/bridge/NavigationReactModule.java

         NavigationCommandsHandler.setScreenTitleBarTitle(screenInstanceId, title);
     }
 
+    @ReactMethod
+    public void setScreenTitleBarSubtitle(String screenInstanceId, String subtitle) {
+        NavigationCommandsHandler.setScreenTitleBarSubtitle(screenInstanceId, subtitle);
+    }
+
     @ReactMethod
     public void setScreenTitleBarButtons(String screenInstanceId, String navigatorEventId,
                                          ReadableArray rightButtonsParams, ReadableMap leftButtonParams) {

android/app/src/main/java/com/reactnativenavigation/controllers/Modal.java

         layout.setTitleBarTitle(screenInstanceId, title);
     }
 
+    public void setTitleBarSubtitle(String screenInstanceId, String subtitle) {
+        layout.setTitleBarSubtitle(screenInstanceId, subtitle);
+    }
+
     public void setTitleBarRightButtons(String screenInstanceId, String navigatorEventId, List<TitleBarButtonParams> titleBarButtons) {
         layout.setTitleBarRightButtons(screenInstanceId, navigatorEventId, titleBarButtons);
     }

android/app/src/main/java/com/reactnativenavigation/controllers/ModalController.java

         }
     }
 
+    public void setTitleBarSubtitle(String screenInstanceId, String subtitle) {
+        for (Modal modal : stack) {
+            modal.setTitleBarSubtitle(screenInstanceId, subtitle);
+        }
+    }
+
     public void setTitleBarRightButtons(String screenInstanceId, String navigatorEventId, List<TitleBarButtonParams> titleBarButtons) {
         for (Modal modal : stack) {
             modal.setTitleBarRightButtons(screenInstanceId, navigatorEventId, titleBarButtons);

android/app/src/main/java/com/reactnativenavigation/controllers/NavigationActivity.java

         modalController.setTitleBarTitle(screenInstanceId, title);
     }
 
+    public void setTitleBarSubtitle(String screenInstanceId, String subtitle) {
+        layout.setTitleBarSubtitle(screenInstanceId, subtitle);
+        modalController.setTitleBarSubtitle(screenInstanceId, subtitle);
+    }
+
     void setTitleBarButtons(String screenInstanceId, String navigatorEventId, List<TitleBarButtonParams> titleBarButtons) {
         layout.setTitleBarRightButtons(screenInstanceId, navigatorEventId, titleBarButtons);
         modalController.setTitleBarRightButtons(screenInstanceId, navigatorEventId, titleBarButtons);

android/app/src/main/java/com/reactnativenavigation/controllers/NavigationCommandsHandler.java

         });
     }
 
+    public static void setScreenTitleBarSubtitle(final String screenInstanceId, final String subtitle) {
+        final NavigationActivity currentActivity = NavigationActivity.currentActivity;
+        if (currentActivity == null) {
+            return;
+        }
+
+        NavigationApplication.instance.runOnMainThread(new Runnable() {
+            @Override
+            public void run() {
+                currentActivity.setTitleBarSubtitle(screenInstanceId, subtitle);
+            }
+        });
+    }
+
     public static void showModal(Bundle params) {
         final NavigationActivity currentActivity = NavigationActivity.currentActivity;
         if (currentActivity == null) {

android/app/src/main/java/com/reactnativenavigation/layouts/BottomTabsLayout.java

         }
     }
 
+    @Override
+    public void setTitleBarSubtitle(String screenInstanceId, String subtitle) {
+        for (int i = 0; i < bottomTabs.getItemsCount(); i++) {
+            screenStacks[i].setScreenTitleBarSubtitle(screenInstanceId, subtitle);
+        }
+    }
+
     @Override
     public void setTitleBarRightButtons(String screenInstanceId, String navigatorEventId, List<TitleBarButtonParams> titleBarButtons) {
         for (int i = 0; i < bottomTabs.getItemsCount(); i++) {

android/app/src/main/java/com/reactnativenavigation/layouts/Layout.java

 
     void setTitleBarTitle(String screenInstanceId, String title);
 
+    void setTitleBarSubtitle(String screenInstanceId, String subtitle);
+
     void setTitleBarRightButtons(String screenInstanceId, String navigatorEventId, List<TitleBarButtonParams> titleBarButtons);
 
     void setTitleBarLeftButton(String screenInstanceId, String navigatorEventId, TitleBarLeftButtonParams titleBarLeftButtonParams);

android/app/src/main/java/com/reactnativenavigation/layouts/SingleScreenLayout.java

         stack.setScreenTitleBarTitle(screenInstanceId, title);
     }
 
+    @Override
+    public void setTitleBarSubtitle(String screenInstanceId, String subtitle) {
+        stack.setScreenTitleBarSubtitle(screenInstanceId, subtitle);
+    }
+
     @Override
     public View asView() {
         return this;

android/app/src/main/java/com/reactnativenavigation/screens/Screen.java

         topBar.setTitle(title);
     }
 
+    public void setTitleBarSubtitle(String subtitle) {
+        topBar.setSubtitle(subtitle);
+    }
+
     public void setTitleBarRightButtons(String navigatorEventId, List<TitleBarButtonParams> titleBarButtons) {
         setButtonColorFromScreen(titleBarButtons);
         topBar.setTitleBarRightButtons(navigatorEventId, titleBarButtons);

android/app/src/main/java/com/reactnativenavigation/screens/ScreenStack.java

         });
     }
 
+    public void setScreenTitleBarSubtitle(String screenInstanceId, final String subtitle) {
+        performOnScreen(screenInstanceId, new Task<Screen>() {
+            @Override
+            public void run(Screen param) {
+                param.setTitleBarSubtitle(subtitle);
+            }
+        });
+    }
+
     public void setScreenTitleBarRightButtons(String screenInstanceId, final String navigatorEventId, final List<TitleBarButtonParams> titleBarButtons) {
         performOnScreen(screenInstanceId, new Task<Screen>() {
             @Override

android/app/src/main/java/com/reactnativenavigation/views/TopBar.java

         titleBar.setTitle(title);
     }
 
+    public void setSubtitle(String subtitle) {
+        titleBar.setSubtitle(subtitle);
+    }
+
     public void setStyle(StyleParams styleParams) {
         if (styleParams.topBarColor.hasColor()) {
             setBackgroundColor(styleParams.topBarColor.getColor());

src/Screen.js

     return platformSpecific.navigatorSetTitle(this, params);
   }
 
+  setSubTitle(params = {}) {
+    return platformSpecific.navigatorSetSubtitle(this, params);
+  }
+
   setTitleImage(params = {}) {
     return platformSpecific.navigatorSetTitleImage(this, params);
   }

src/deprecated/platformSpecificDeprecated.android.js

   newPlatformSpecific.setScreenTitleBarTitle(navigator.screenInstanceID, params.title);
 }
 
+function navigatorSetSubtitle(navigator, params) {
+  newPlatformSpecific.setScreenTitleBarSubtitle(navigator.screenInstanceID, params.subtitle);
+}
+
 function navigatorSwitchToTab(navigator, params) {
   if (params.tabIndex >= 0) {
     newPlatformSpecific.selectBottomTabByTabIndex(params.tabIndex);
   navigatorSetButtons,
   navigatorSetTabBadge,
   navigatorSetTitle,
+  navigatorSetSubtitle,
   navigatorSwitchToTab,
   navigatorToggleDrawer,
   navigatorToggleTabs,

src/platformSpecific.android.js

   NativeReactModule.setScreenTitleBarTitle(screenInstanceID, title);
 }
 
+function setScreenTitleBarSubtitle(screenInstanceID, subtitle) {
+  NativeReactModule.setScreenTitleBarSubtitle(screenInstanceID, subtitle);
+}
+
 function setScreenTitleBarButtons(screenInstanceID, navigatorEventID, rightButtons, leftButton) {
   NativeReactModule.setScreenTitleBarButtons(screenInstanceID, navigatorEventID, rightButtons, leftButton);
 }
   toggleTopBarVisible,
   toggleBottomTabsVisible,
   setScreenTitleBarTitle,
+  setScreenTitleBarSubtitle,
   setScreenTitleBarButtons,
   showModal,
   dismissTopModal,