Attempts at implementing background tasks in React Native iOS

BackgroundTask.h

//
//  BackgroundTask.h
//  tomtrack
//
//  Created by Liam Edwards-Playne on 13/02/2016.
//

#import "RCTBridgeModule.h"

@interface BackgroundTask : NSObject <RCTBridgeModule>

@end

BackgroundTask.m

//
//  BackgroundTask.m
//  tomtrack
//
//  Created by Liam Edwards-Playne on 13/02/2016.
//

#import <Foundation/Foundation.h>

#import "BackgroundTask.h"
#import "RCTUtils.h"


/*
 Sample: 
 
 BackgroundTask.beginBackgroundTask("gpsTracking", () => {})
 
 */

@implementation BackgroundTask


RCT_EXPORT_MODULE();

#pragma mark - Public API

RCT_EXPORT_METHOD(beginBackgroundTask:(NSString *)taskName jsCallback:(RCTResponseSenderBlock)jsCallback)
{
  UIApplication *application = RCTSharedApplication();
  
  __block UIBackgroundTaskIdentifier bgTask = [application beginBackgroundTaskWithName:taskName expirationHandler:^{
    // Clean up any unfinished task business by marking where you
    // stopped or ending the task outright.
    [application endBackgroundTask:bgTask];
    bgTask = UIBackgroundTaskInvalid;
  }];
  
  // Start the long-running task and return immediately.
  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    printf("Running in the background\n");
    // Call the JS code
    jsCallback(@[]);
    printf("Back from the JS\n");
    
    [application endBackgroundTask:bgTask];
    bgTask = UIBackgroundTaskInvalid;
  });
}

@end

example.js

var BackgroundTask = require('react-native').NativeModules.BackgroundTask;
BackgroundTask.beginTask("taskName", function(){})

Inspired by some work from these guys https://github.com/transistorsoft/react-native-background-geolocation/blob/c1cd452751ffa8a4985b2302933c24d2033b35be/RNBackgroundGeolocation/RNBackgroundGeolocation.m

Do you think this would allow me to maintain a socket connection in the background, while my screen is off? I have been trying to make a running app that communicates with a server with socket, http://stackoverflow.com/questions/35458549/how-to-run-socket-io-in-the-background-on-ios-in-a-react-native-app, but I can't find a way to keep the socket connection alive. I've even tried the react-native-background-geolocation, but ran into different problems there.

Hi, do you have any more information on how to use this? Is it suppose to be used as an request Animation frame? Thanks.

@easilyBaffled Hey, did you succeed in maintaining a socket connection in the background? I'm looking for a way to do that.

@easilyBaffled @arvindnrbt @puredazzle any update? did you manage to keep the socket connection alive?