在CMMotionActivity发生变化时，是否有办法在后台通知我的应用程序？

Question

I'd like to know if the system can wake an application in the background if the CMMotionActivity changes, for example, if the user starts walking/running after sitting, I'd like to be able to execute some code and schedule a local notification.

Is there a way to ask the system to wake my app in the background for that ?

EDIT : By looking at the reference , it doesn't seem to be possible ("[...] and updates are not delivered while your app is suspended.") , but maybe is there an other way ?

Answer 1

I solved this creating a background timer and checking for the activity type in the selector called method. Just have a look to the code in case it can be useful for you. I accept suggestions, corrections and advices over this.

#define k_timer_time 10.0f
@property NSTimer *timer;

- (void) createBackGroundTimerToCheckMotion{
// create new uiBackgroundTask
__block UIBackgroundTaskIdentifier bgTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
    [[UIApplication sharedApplication]  endBackgroundTask:bgTask];
    bgTask = UIBackgroundTaskInvalid;
}];

__weak __typeof(self) weakSelf = self;

// and create new timer with async call:
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    weakSelf.timer = [NSTimer scheduledTimerWithTimeInterval:k_timer_time target:self selector:@selector(onTick:) userInfo:nil repeats:YES];
    weakSelf.timer.tolerance = 5;
    [[NSRunLoop currentRunLoop] addTimer:weakSelf.timer forMode:NSDefaultRunLoopMode];
    [[NSRunLoop currentRunLoop] run];
});

}

- (void) onTick:(NStimer*)timer{
if([CMMotionActivityManager isActivityAvailable])
{
    __weak __typeof(self) weakSelf = self;

    CMMotionActivityManager *cm = [[CMMotionActivityManager alloc] init];

    CMPedometer *sc = [[CMPedometer alloc] init];

    NSDate *now = [NSDate date];

    NSDate *last30Sec = [now dateByAddingTimeInterval:-30];

    [cm queryActivityStartingFromDate:last30Sec toDate:now toQueue:[NSOperationQueue mainQueue] withHandler:^(NSArray *activities, NSError *error)
     {
         [activities enumerateObjectsUsingBlock:^(CMMotionActivity *a, NSUInteger idx, BOOL * _Nonnull stop) {
              //Your stuff here

         }];
     }];
}
else
{
    NSLog(@"Error accessing Motion data");
}

}