NSMutableArray randomly releasing objects - ios

Question

With my app the user can record a drive using LocationManager while on the road for different calculation purposes. These calculations are done in the Class Calculator. This usually works fine except for sometimes when apparently the NSMutableArrays energyArray and energyOnlyDriveArray looses all if its stored values which are then written as nil int Core Data.
Here is the code:
DriveView Loads
DriveView.h
#interface DriveView : UIScrollView <ADBannerViewDelegate,CLLocationManagerDelegate,CalculatorDelegate>
{
Calculator *calculator;
}
#property (nonatomic, strong) Calculator *calculator;
DriveView.m
#implementation DriveView
#synthesize calculator = _calculator;
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
_calculator = [[Calculator alloc]init];
_calculator.delegate = self;
}
return self;
}
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
[_calculator locationManagerDidUpdateLocations:locations];
}
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
[_calculator locationManagerDidFailWithError:error];
}
User starts recording
DriveView tells the location manager to start updating locations and calls initData and initCarData when the user starts to record a drive.
Calculator.h
#interface Calculator : NSObject {
#private
NSMutableArray *energyArray;
NSMutableArray *energyOnlyDriveArray;
}
#property (strong, nonatomic) id <CalculatorDelegate> delegate;
#property (strong, nonatomic) NSManagedObjectContext *managedObjectContext;
#property (nonatomic, strong) dispatch_queue_t queue;
#property (nonatomic, strong) NSMutableArray *alt_filtered;
#property (nonatomic, strong) NSMutableArray *energyArray;
#property (nonatomic, strong) NSMutableArray *energyOnlyDriveArray;
#property (nonatomic, strong) NSMutableDictionary *powerVectorDict;
#property (nonatomic, strong) NSMutableArray *carSpecificData;
- (void)initData;
- (void)initCarData;
...
Calculator.m
#implementation Calculator
#synthesize managedObjectContext = __managedObjectContext;
#synthesize energyArray = _energyArray;
#synthesize energyOnlyDriveArray = _energyOnlyDriveArray;
- (id)init
{
if (self = [super init])
{
_queue = dispatch_queue_create(NULL, NULL);
}
return self;
}
- (void)initData
{
self.managedObjectContext = [kDelegate managedObjectContext];
}
- (void)initCarData
{
_energyArray = [[NSMutableArray alloc]init]; //stores the energy values
_energyOnlyDriveArray = [[NSMutableArray alloc]init]; //stores the energy values
_carSpecificData = [[NSMutableArray alloc]init];
_alt_filtered = [[NSMutableArray alloc]init];
for (int i = 0; i < [[[Cars manager]carsList] count]; i++) {
[_energyArray addObject:[NSNumber numberWithFloat:0.0f]];
[_energyOnlyDriveArray addObject:[NSNumber numberWithFloat:0.0f]];
[_carSpecificData addObject:[NSDictionary new]];
}
....
}
- (void)locationManagerDidUpdateLocations:(NSArray *)locations
{
CLLocation *newLocation = [locations lastObject];
if ((newLocation.horizontalAccuracy > 0) && (newLocation.verticalAccuracy > 0) && (newLocation.horizontalAccuracy < 100) && (newLocation.verticalAccuracy < 100))
{
--> Some code and then `launchAlgorithm:`
}
}
- (void)launchAlgorithm:(Drive*)drive
{
UIApplication* app = [UIApplication sharedApplication];
// Request permission to run in the background. Provide an // expiration handler in case the task runs long.
UIBackgroundTaskIdentifier bgTask = UIBackgroundTaskInvalid;
bgTask = [app beginBackgroundTaskWithExpirationHandler: ^{
[app endBackgroundTask:bgTask];
}];
dispatch_async(_queue, ^{
#autoreleasepool {
for (int i = 0; i < [[[Cars manager]carsList] count]; i++) {
[self processAlgorithmResults:[Algorithm that calculation and returns NSDictionary]];
}
if (bgTask != UIBackgroundTaskInvalid) {
dispatch_async(_queue, ^{
[app endBackgroundTask:bgTask];
});
}
}
});
- (void)processAlgorithmResults:(NSMutableDictionary *)driverProfile
{
// write energy into array
float energyValue = [[_energyArray objectAtIndex:i]floatValue] + [[driverProfile objectForKey:#"EVerbrauch"] floatValue];
[_energyArray replaceObjectAtIndex:i withObject:[NSNumber numberWithFloat:energyValue]];
float energyOnlyDriveValue = [[_energyOnlyDriveArray objectAtIndex:i]floatValue] + [[driverProfile objectForKey:#"EVerbrauchOnlyDrive"] floatValue];
[_energyOnlyDriveArray replaceObjectAtIndex:i withObject:[NSNumber numberWithFloat:energyOnlyDriveValue]];
// set power value
NSMutableArray *powerValueArray = [NSMutableArray arrayWithArray:[_powerVectorDict objectForKey:[NSNumber numberWithInteger:i]]];
[powerValueArray addObject:[[driverProfile objectForKey:#"P"]valueForKey:#"Pel_drive"]];
[_powerVectorDict setObject:powerValueArray forKey:[NSNumber numberWithInteger:i]];
}
AFTER THE DRIVE IS DONE EVERYTHING IS SAVED LIKE THIS:
- (void)saveHistory
{
for (int i = 0; i < [[[Cars manager]carsList] count]; i++) {
// power array of the car
NSMutableArray *powerArray = [_powerVectorDict objectForKey:[NSNumber numberWithInt:i]];
History *history = (History *)[NSEntityDescription insertNewObjectForEntityForName:#"History" inManagedObjectContext:self.managedObjectContext];
history.driveID = [[Settings manager]lastDriveID];
history.distance = [NSNumber numberWithFloat:_totalDistance];
history.vMax = [NSNumber numberWithFloat:_maxSpeed];
history.driveDate = firstTime;
history.sentToServer = [NSNumber numberWithBool:NO];
history.vMean = [NSNumber numberWithFloat:_avgSpeed];
history.energy = [NSNumber numberWithFloat:[[_energyArray objectAtIndex:i]floatValue]];
history.energy_onlyDrive = [NSNumber numberWithFloat:[[_energyOnlyDriveArray objectAtIndex:i]floatValue]];
history.car = [[[[Cars manager]carsList] objectAtIndex:i] objectForKey:#"name"];
history.carID = [NSNumber numberWithInt:i];
history.area = [[[[Cars manager]carsList] objectAtIndex:i] objectForKey:#"area"];
history.cw = [[[[Cars manager]carsList] objectAtIndex:i] objectForKey:#"cw"];
history.weight = [[[[Cars manager]carsList] objectAtIndex:i] objectForKey:#"weight"];
history.driveDuration = [NSNumber numberWithFloat:[lastTime timeIntervalSinceDate:firstTime]];
history.temperature = [[Settings manager]localTemperature];
history.temperatureSystem = [[Settings manager]temperatureSystem];
history.precision = [NSNumber numberWithFloat:(((float)_totalSignals-(float)_badSignals))/(float)_totalSignals];
history.includeInProfile = [NSNumber numberWithBool:YES];
history.maxPower = [NSNumber numberWithFloat:[[powerArray objectAtIndex:index]floatValue]];
history.lastSentChunk = [NSNumber numberWithFloat:0];
}
if (self.managedObjectContext != nil)
{
NSError *error;
if (![self.managedObjectContext save:&error]) {
NSLog(#"error: %#",error.description);
NSLog(#"error: %#",error);
}
}
}
Now when I retrieve the data the values for history.energy and history.energy_onlyDrive return nil value.
The app can also run in the background and will do all the calculations there as well.
I hope somebody can help me out here. I really cant see why the arrays are being cleared which seems kind of random because sometimes it happens and sometimes it doesnt. I is also not relevant how long the calculations go. I have it happen when doing a 3 minute drive as well as a 3 hour drive.
Thanks a lot for your help!