reset buttons to avoid react component recreation

lib/ios/RNNTopBarOptions.m

 	
 	viewController.navigationItem.hidesBackButton = [self.backButtonHidden boolValue];
 	
+	[self resetOptions];
+}
+
+- (void)resetOptions {
+	self.leftButtons = nil;
+	self.rightButtons = nil;
 }
 
 -(void)storeOriginalTopBarImages:(UIViewController*)viewController {