iOS equivalent to Android Service?

Question

So with iOS 7 supporting a broader background mode, is it possible to finally have an equivalent to Android Service on iOS?

What I am after is essentially running app A in the background and have one or more apps B and C talk to that app (without showing the GUI of app A).

Please note that using connectivity and push notifications may not be an option although this is the recommended way of doing so. Any ideas?

Answer 1

EDIT: Not working as expected. See this answer for best solution: Push Notifications

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EDIT: The next solution is only useful while the user is in the app to maintain it synced.

There is no way to perform tasks in the background permanently, but you can use the finite-length tasks to do that, when you make a finite-length, this gonna run always while the app is active, but when you click home button, ios gives you only 10 min to perform your task and invalidate it, but it gives you a chance to make a 'invalidate handler block' where you can do last actions before finish definitely.

So, if you use that handler block to call a finite-length task other time, you can simulate a service by run a task for 10 min and when its end, call its same for other 10 min and consequently.

I use that in a project creating a interface 'Service'. I let you here the code:

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• Service.h

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//
//  Service.h
//  Staff5Personal
//
//  Created by Mansour Boutarbouch Mhaimeur on 30/09/13.
//  Copyright (c) 2013 Smart & Artificial Technologies. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Service : NSObject

@property (nonatomic) UIBackgroundTaskIdentifier backgroundTask;
@property (nonatomic) NSInteger frequency;
@property (nonatomic, strong) NSTimer *updateTimer;

- (id) initWithFrequency: (NSInteger) seconds;
- (void) startService;
- (void) doInBackground;
- (void) stopService;
@end

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• Service.m

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//
//  Service.m
//  Staff5Personal
//
//  Created by Mansour Boutarbouch Mhaimeur on 30/09/13.
//  Copyright (c) 2013 Smart & Artificial Technologies. All rights reserved.
//

#import "Service.h"

@implementation Service
@synthesize frequency;

-(id)initWithFrequency: (NSInteger) seconds{
    if(self = [super init]){        
        self.frequency = seconds;
        return self;
    }
    return nil;
}
- (void)startService{
    [self startBackgroundTask];
}

- (void)doInBackground{
    //Español //Sobreescribir este metodo para hacer lo que quieras
    //English //Override this method to do whatever you want
}

- (void)stopService{
    [self.updateTimer invalidate];
    self.updateTimer = nil;
    [[UIApplication sharedApplication] endBackgroundTask:self.backgroundTask];
    self.backgroundTask = UIBackgroundTaskInvalid;
}

- (void) startBackgroundTask{
    self.updateTimer = [NSTimer scheduledTimerWithTimeInterval:frequency
                                                        target:self
                                                      selector:@selector(doInBackground)
                                                      userInfo:nil
                                                       repeats:YES];
    self.backgroundTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
        [self endBackgroundTask];
    }];
}
- (void) endBackgroundTask{
    [self.updateTimer invalidate];
    self.updateTimer = nil;
    [[UIApplication sharedApplication] endBackgroundTask:self.backgroundTask];
    self.backgroundTask = UIBackgroundTaskInvalid;
    [self startBackgroundTask];
}

@end

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With this class i perform my services, but i don't test it for a really long time. The best test i does lasted 16 hours in simulator and everything works fine!

EDIT: That was tested on the simulator, but in phone doesnt work after the application has been terminated.

I let you a example:

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// SomeService.h
@interface SomeService : Service

@end


// SomeService.m
#import "SomeService.h"

@implementation SomeService

// The method to override
- (void)doInBackground{
    NSLog(@"Background time remaining = %.1f seconds", [UIApplication sharedApplication].backgroundTimeRemaining);
    NSLog(@"Service running at %.1f seconds", [self getCurrentNetworkTime]);
}
// Your methods
- (long) getCurrentNetworkTime{
    return ([[NSDate date] timeIntervalSince1970]);
}

@end

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And in your app delegate or where you need to raise the service, you write the next line:

Service myService = [[SomeService alloc] initWithFrequency: 60]; //execute doInBackground each 60 seconds
[myService startService];

And if you need to stop it:

[myService stopService];

May have explained more than necessary, but i want to keep it clear for anyone! I hope its help and sorry for my english.

Answer 2

No, there is no equivalent to an Android Service. MansApps code does not work, at least not on iOS7. A call of [[UIApplication sharedApplication] endBackgroundTask:self.backgroundTask]; in the expiration handler will only return when the app comes back to the foreground, i.e., the call of [self startBackgroundTask]; will not be executed when the app stays in the background.