fix(ios): fix embedding in parent container(#244)

Author: gabrielbull

ios/ReactNativePageView.m

@@ -55,14 +55,30 @@ - (void)layoutSubviews {
 }
 
 - (void)didUpdateReactSubviews {
-    if (!self.reactPageViewController) {
+    if (!self.reactPageViewController && self.reactViewController != nil) {
         [self embed];
         [self setupInitialController];
     } else {
         [self updateDataSource];
     }
 }
 
+- (void)didMoveToSuperview {
+    [super didMoveToSuperview];
+    if (!self.reactPageViewController && self.reactViewController != nil) {
+        [self embed];
+        [self setupInitialController];
+    }
+}
+
+- (void)didMoveToWindow {
+    [super didMoveToWindow];
+    if (!self.reactPageViewController && self.reactViewController != nil) {
+        [self embed];
+        [self setupInitialController];
+    }
+}
+
 - (void)embed {
     NSDictionary *options = @{ UIPageViewControllerOptionInterPageSpacingKey: @(self.pageMargin) };
     UIPageViewController *pageViewController = [[UIPageViewController alloc] initWithTransitionStyle:self.transitionStyle