RCT_EXPORT_METHOD(addEvent:(NSString *)name location:(NSString *)location)
{
 RCTLogInfo(@"Pretending to create an event %@ at %@", name, location);
}

import {NativeModules} from 'react-native';
var CustomName = NativeModules.CalendarManager;
CustomName.addEvent('Birthday Party', '4 Privet Drive, Surrey');

RCT_EXPORT_METHOD(findEvents:(RCTResponseSenderBlock)callback)
{
 NSArray *events = ...
 callback(@[[NSNull null], events]);
}

CalendarManager.findEvents((error, events) => {
 if (error) {
 console.error(error);
 } else {
 this.setState({events: events});
 }
});

RCT_REMAP_METHOD(findEvents,
     findEventsWithResolver:(RCTPromiseResolveBlock)resolve
     rejecter:(RCTPromiseRejectBlock)reject)
{
 NSArray *events = ...
 if (events) {
 resolve(events);
 } else {
 NSError *error = ...
 reject(@"no_events", @"There were no events", error);
 }
}

async function updateEvents() {
 try {
 var events = await CalendarManager.findEvents();

 this.setState({events});
 } catch (e) {
 console.error(e);
 }
}

updateEvents();

- (dispatch_queue_t)methodQueue
{
 return dispatch_get_main_queue();
}

- (NSDictionary *)constantsToExport
{
 return @{ @"firstDayOfTheWeek": @"Monday" };
}

@implementation RCTConvert (StatusBarAnimation)
 RCT_ENUM_CONVERTER(UIStatusBarAnimation, (@{ @"statusBarAnimationNone" : @(UIStatusBarAnimationNone),
            @"statusBarAnimationFade" : @(UIStatusBarAnimationFade),
            @"statusBarAnimationSlide" : @(UIStatusBarAnimationSlide)}),
      UIStatusBarAnimationNone, integerValue)
@end

RCT_EXPORT_MODULE();

- (NSArray<NSString *> *)supportedEvents
{
 return @[@"EventReminder"];
}

- (void)calendarEventReminderReceived:(NSNotification *)notification
{
 NSString *eventName = notification.userInfo[@"name"];
 [self sendEventWithName:@"EventReminder" body:@{@"name": eventName}];
}

import { NativeEventEmitter, NativeModules } from 'react-native';
const { CalendarManager } = NativeModules;

const calendarManagerEmitter = new NativeEventEmitter(CalendarManager);

const subscription = calendarManagerEmitter.addListener(
 'EventReminder',
 (reminder) => console.log(reminder.name)
);
...
// Don't forget to unsubscribe, typically in componentWillUnmount
subscription.remove();

// Will be called when this module's first listener is added.
-(void)startObserving {
 hasListeners = YES;
 // Set up any upstream listeners or background tasks as necessary
}

// Will be called when this module's last listener is removed, or on dealloc.
-(void)stopObserving {
 hasListeners = NO;
 // Remove upstream listeners, stop unnecessary background tasks
}