Core Data: Custom Setter Which Does Cascading Calculation Failing

Question

I have a class called Location with the following automatically generated declaration,

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>

@interface Location : NSManagedObject

@property (nonatomic, retain) NSNumber * cosRadLat;
@property (nonatomic, retain) NSNumber * latitude;
@property (nonatomic, retain) NSNumber * longitude;
@property (nonatomic, retain) NSNumber * radLat;
@property (nonatomic, retain) NSNumber * radLng;
@property (nonatomic, retain) NSNumber * sinRadLat;

@end

In an objective-c category, I have created two methods to calculate the other properties based on the latitude and longitude,

- (double)degreesToRadians:(NSNumber *)degrees
{
    double radians = ([degrees doubleValue] * M_PI) / 180.0;
    return radians;
}

- (void)setLatitude:(NSNumber *)newLat longitude:(NSNumber *)newLng
{
    [self setLatitude:newLat];
    [self setLongitude:newLng];

    // Make calculations
    double dblRadLat = [self degreesToRadians:newLat];
    double dblRadLng = [self degreesToRadians:newLng];
    double dblCosRadLat = cos(dblRadLat);
    double dblSinRadLat = sin(dblRadLat);

    // and set their values
    [self setRadLat:[NSNumber numberWithDouble:dblRadLat]];
    [self setRadLng:[NSNumber numberWithDouble:dblRadLng]];
    [self setCosRadLat:[NSNumber numberWithDouble:dblCosRadLat]];
    [self setSinRadLat:[NSNumber numberWithDouble:dblSinRadLat]];
}

When I run my unit tests, half the time I get this:

Lat 40.7302133
Lng -74.0003337
RadLat 0.7108763271245849
RadLng -1.291549470639518
CosRadLat 0.7577903652576623
SinRadLat 0.6524980937310535

The other half, I get this:

Lat 40.7302133
Lng -74.0003337
RadLat 0
RadLng 0
CosRadLat 0
SinRadLat 0

What am I doing wrong?

UNIT TEST

Here is my function I use to save the context in the unit test,

- (void)saveContext
{
    NSLog(@"%@ saveContext", self.name);

    NSError *saveError = nil; 
    STAssertTrue([self.managedObjectContext save:&saveError], @"Failed to save context to persistent store: %@", saveError);
}

And here is how I am calling it,

// Constants we will check to ensure our calcluations are correct
// 1st Location
double const LAT = 40.7292540;
double const LNG = -73.9988530;
double const RAD_LAT = 0.710859584;
double const RAD_LNG = -1.29152363;
double const SIN_RAD_LAT = 0.652485406;
double const COS_RAD_LAT = 0.75780129;
double const accuracy = 0.00000001;

/** Run before each test. Populates the database with objects to play with.
 */
- (void)setUp
{
    NSLog(@"%@ setUp", self.name);

    // Creates our persistent store in memory and initializes our managed object context for us.
    [super setUp];

    // Create a new Location
    Location *location = [NSEntityDescription insertNewObjectForEntityForName:@"Location" inManagedObjectContext:self.managedObjectContext];

    // Using the setLatitude:longitude: method, which cascades the calculation for all other values
    [location setLatitude:[NSNumber numberWithDouble:LAT] longitude:[NSNumber numberWithDouble:LNG]];

    // Check if it has properly calculated the values we asked for
    double lat = [[location latitude] doubleValue];
    double lng = [[location longitude] doubleValue];
    double rad_lat = [[location radLat] doubleValue];
    double rad_lng = [[location radLng] doubleValue];
    double sin_rad_lat = [[location sinRadLat] doubleValue];
    double cos_rad_lat = [[location cosRadLat] doubleValue];

    STAssertEqualsWithAccuracy(LAT, lat, accuracy, @"Wanted: %f Got: %f", LAT, lat);
    STAssertEqualsWithAccuracy(LNG, lng, accuracy, @"Wanted: %f Got: %f", LNG, lng);
    STAssertEqualsWithAccuracy(RAD_LAT, rad_lat, accuracy, @"Wanted: %f Got: %f", RAD_LAT, rad_lat);
    STAssertEqualsWithAccuracy(RAD_LNG, rad_lng, accuracy, @"Wanted: %f Got: %f", RAD_LNG, rad_lng);
    STAssertEqualsWithAccuracy(SIN_RAD_LAT, sin_rad_lat, accuracy, @"Wanted: %f Got: %f", SIN_RAD_LAT, sin_rad_lat);
    STAssertEqualsWithAccuracy(COS_RAD_LAT, cos_rad_lat, accuracy, @"Wanted: %f Got: %f", COS_RAD_LAT, cos_rad_lat);

    // Saves the managed object context into the persistent store.
    [self saveContext];
}

This part usually works. What happens is, setup is called, it runs this test, and here is where it fails,

- (Location *)fetchLastLocation
{
    NSLog(@"%@ getLastLocation", self.name);

    NSMutableArray *mutableFetchResults = [self fetchEntity: @"Location"];

    Location *location = (Location *)[mutableFetchResults lastObject];

    return location;
}

/** Tests to see if the values stick after saving and fetching
 */
- (void)testCalculatedValuesStick
{
    Location *location = [self fetchLastLocation];

    NSLog(@"Stick: %@", location);

    // Check if it has properly calculated the values we asked for
    double lat = [[location latitude] doubleValue];
    double lng = [[location longitude] doubleValue];
    double rad_lat = [[location radLat] doubleValue];
    double rad_lng = [[location radLng] doubleValue];
    double sin_rad_lat = [[location sinRadLat] doubleValue];
    double cos_rad_lat = [[location cosRadLat] doubleValue];

    STAssertEqualsWithAccuracy(LAT, lat, accuracy, @"Wanted: %f Got: %f", LAT, lat);
    STAssertEqualsWithAccuracy(LNG, lng, accuracy, @"Wanted: %f Got: %f", LNG, lng);
    STAssertEqualsWithAccuracy(RAD_LAT, rad_lat, accuracy, @"Wanted: %f Got: %f", RAD_LAT, rad_lat);
    STAssertEqualsWithAccuracy(RAD_LNG, rad_lng, accuracy, @"Wanted: %f Got: %f", RAD_LNG, rad_lng);
    STAssertEqualsWithAccuracy(SIN_RAD_LAT, sin_rad_lat, accuracy, @"Wanted: %f Got: %f", SIN_RAD_LAT, sin_rad_lat);
    STAssertEqualsWithAccuracy(COS_RAD_LAT, cos_rad_lat, accuracy, @"Wanted: %f Got: %f", COS_RAD_LAT, cos_rad_lat);
}

Do you think my unit test has anything to do with it?

Answer 1

I noticed your method is making variables named radLat, but that is also a property of your instance - I feel like you may have pointer troubles happening.

Try changing the name of your method variables (double radLat etc) to something different and see if that changes how your code is running. I think that code isn't behaving the way you're expecting it to - though knowing more about the code operating on your Location class will help.