iOS User steps count - ios

Question

I am working on the iPhone app in Objective-C in which I count steps of user by using CMAccelerometerData.
It works fine when app is running in background ,
But when I kill my app (double-clicking the Home button and then swiping app away) then I can not get the steps count.
The feature of app is that fetch steps count if my app is in kill state (double-clicking the Home button and then swiping app away) and I run it from icon.
Is there any way to get steps count if our app is killed (double-clicking the Home button and then swiping app away) ?
Here is the method to get steps
- (void)startDetectionWithUpdateBlock:(void (^)(NSError *))callback
{
if (self.motionManager.isAccelerometerActive) {
return;
}
[self.motionManager startAccelerometerUpdatesToQueue:self.queue withHandler:^(CMAccelerometerData *accelerometerData, NSError *error) {
if (error) {
if (callback) {
dispatch_async(dispatch_get_main_queue(), ^{
callback (error);
});
}
return ;
}
CMAcceleration acceleration = accelerometerData.acceleration;
CGFloat strength = 1.2f;
BOOL isStep = NO;
if (fabs(acceleration.x) > strength || fabs(acceleration.y) > strength || fabs(acceleration.z) > strength) {
isStep = YES;
}
if (isStep) {
if (callback) {
dispatch_async(dispatch_get_main_queue(), ^{
callback (nil);
});
}
}
}];
}
And through this way I update steps count :
[[SOLocationManager sharedInstance] start];
[[SOStepDetector sharedInstance] startDetectionWithUpdateBlock:^(NSError *error) {
if (error) {
NSLog(#"%#", error.localizedDescription);
return;
}
self.actualCheckpoint.stepsCount ++;
NSLog(#"Total Steps: %ld",(long)self.actualCheckpoint.stepsCount);
[[NSNotificationCenter defaultCenter] postNotificationName:SBCompetitionStepsCountDidChange object:self.actualCheckpoint];
}];

Answer 1

you can catch the data in appDelegate's
- (void)applicationWillTerminate:(UIApplication *)application {}

Answer 2

You can't access HealthKit data in the background when the device is locked, according to Apple:
For security, the HealthKit store is encrypted when the device is locked. The HealthKit store can only be accessed by an authorized app. As a result, you may not be able to read data from the store when your app is launched in the background; however, apps can still write data to the store, even when the phone is locked. HealthKit temporarily caches the data and saves it to the encrypted store as soon as the phone is unlocked.
https://developer.apple.com/library/ios/documentation/HealthKit/Reference/HealthKit_Framework/
You'll need to read the data on startup to 'catch up' from the last time your app was run.

Answer 3

If the app is killed by the user by swiping up, rather than by simply putting the app into the background, it is no longer allows to execute any code until the user opens it again. However, there's no way to get direct access to the accelerometer if the app is completely killed.
There are ways to handle keeping the app open indefinitely if it goes into the background (not manually killed by the user). However, having the accelerometer powered up constantly would be a significant battery drain, and if all you want to do it track steps, you can simply use the HealthKit API. (If you need your app to work on old devices, you will have to resort to background processing.)
HealthKit
As an Apple OS-level API, HealthKit is always working and (if the user's device supports it and the user hasn't disabled it) is constantly tracking steps in the background, using Apple's accurate, battery efficient algorithm (it uses the device's motion coprocessor).
All you need to do is integrate your app with HealthKit such that it can read the device's Steps metric. Take a look at this objective-C tutorial.