android onDisappear

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/ViewController.java

 	private final String id;
 	private View view;
 	private StackController parentStackController;
-	private boolean appeared = false;
+	private boolean isShown = false;
 
 	public ViewController(Activity activity, String id) {
 		this.activity = activity;
 
 	@Override
 	public void onGlobalLayout() {
-		if (!appeared && getView().isShown()) {
-			appeared = true;
+		if (!isShown && getView().isShown()) {
+			isShown = true;
 			onAppear();
+		} else if (isShown && !getView().isShown()) {
+			isShown = false;
+			onDisappear();
 		}
 	}
 }

lib/android/app/src/test/java/com/reactnativenavigation/viewcontrollers/ViewControllerTest.java

 		Assertions.assertThat(spy.getView()).isNotShown();
 		verify(spy, times(1)).onDisappear();
 	}
+
+	@Test
+	public void onDisappear_CalledAtMostOnce() throws Exception {
+		ViewController spy = spy(uut);
+		Shadows.shadowOf(spy.getView()).setMyParent(mock(ViewParent.class));
+		Assertions.assertThat(spy.getView()).isShown();
+		spy.getView().getViewTreeObserver().dispatchOnGlobalLayout();
+		spy.getView().setVisibility(View.GONE);
+		spy.getView().getViewTreeObserver().dispatchOnGlobalLayout();
+		spy.getView().getViewTreeObserver().dispatchOnGlobalLayout();
+		spy.getView().getViewTreeObserver().dispatchOnGlobalLayout();
+		verify(spy, times(1)).onDisappear();
+	}
 }