Add lifecycle aware view managers to Example app

Example/ios/ScreensExample/RNSSampleLifecycleAwareView.m

@@ -0,0 +1,33 @@
+#import <React/RCTViewManager.h>
+
+@interface RNSLifecycleAwareView : UIView
+@end
+
+@implementation RNSLifecycleAwareView
+
+- (void)didMoveToWindow
+{
+  [super didMoveToWindow];
+  BOOL isVisible = self.superview && self.window;
+  if (isVisible) {
+    NSLog(@"ATTACHED");
+  } else {
+    NSLog(@"DETTACHED");
+  }
+}
+
+@end
+
+@interface RNSLifecycleAwareViewManager : RCTViewManager
+@end
+
+@implementation RNSLifecycleAwareViewManager
+
+RCT_EXPORT_MODULE()
+
+- (UIView *)view
+{
+  return [RNSLifecycleAwareView new];
+}
+
+@end