Experimental change to StackView. Prevent screens from getting unmounted when removing them from screen

android/app/src/main/java/com/reactnativenavigation/utils/ReflectionUtils.java

+package com.reactnativenavigation.utils;
+
+import java.lang.reflect.Field;
+
+/**
+ * Created by guyc on 14/04/16.
+ */
+public class ReflectionUtils {
+
+    public static boolean setBooleanField(Object obj, String name, Boolean value) {
+        Field field;
+        try {
+            field = obj.getClass().getDeclaredField(name);
+            field.setAccessible(true);
+            field.set(obj, value);
+            return true;
+        } catch (NoSuchFieldException e) {
+            e.printStackTrace();
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        }
+        return false;
+    }
+}

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

  */
 public class RctView extends FrameLayout {
 
+    private ReactRootView mReactRootView;
+
+    public ReactRootView getReactRootView() {
+        return mReactRootView;
+    }
+
     public RctView(BaseReactActivity ctx, ReactInstanceManager rctInstanceManager, Screen screen) {
         super(ctx);
         setLayoutParams(new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
 
-        ReactRootView root = new ReactRootView(ctx);
-        root.setLayoutParams(new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
+        mReactRootView = new ReactRootView(ctx);
+        mReactRootView.setLayoutParams(new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
 
         String componentName = screen.screenId;
         Bundle passProps = new Bundle();
         passProps.putString(Screen.KEY_NAVIGATOR_ID, screen.navigatorId);
         passProps.putString(Screen.KEY_NAVIGATOR_EVENT_ID, screen.navigatorEventId);
 
-        root.startReactApplication(rctInstanceManager, componentName, passProps);
+        mReactRootView.startReactApplication(rctInstanceManager, componentName, passProps);
 
-        addView(root);
+        addView(mReactRootView);
     }
 }
 

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

 import android.widget.FrameLayout;
 
 import com.facebook.react.ReactInstanceManager;
+import com.facebook.react.ReactRootView;
 import com.reactnativenavigation.activities.BaseReactActivity;
 import com.reactnativenavigation.core.RctManager;
 import com.reactnativenavigation.core.objects.Screen;
+import com.reactnativenavigation.utils.ReflectionUtils;
 
 import java.util.Stack;
 
-import static android.view.ViewGroup.LayoutParams.*;
+import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
 
 public class ScreenStack extends FrameLayout {
 
         }
         RctView view = new RctView(reactActivity, mReactInstanceManager, screen);
         addView(view, MATCH_PARENT, MATCH_PARENT);
-        if(oldView!=null) {
-            oldView.setVisibility(GONE);
+        if(oldView != null) {
+            ReactRootView reactRootView = ((RctView) oldView).getReactRootView();
+            ReflectionUtils.setBooleanField(reactRootView, "mAttachScheduled", true);
+            removeView(oldView);
         }
         stack.push(new ScreenView(screen, view));
     }
         }
         ScreenView popped = stack.pop();
         if(!stack.isEmpty()) {
-            View view = stack.peek().view;
-            if(view.getParent() == null)
-                addView(stack.peek().view, 0);
-            else {
-                view.setVisibility(VISIBLE);
-            }
+            addView(stack.peek().view, 0);
         }
         removeView(popped.view);
         return popped.screen;