Question

I have this object:

@interface Song : NSManagedObject

@property (nonatomic, strong) NSString *songName;
@property (nonatomic) int32_t achievedPoints;

When I set the properties like this

Song *song1 = [[SongStore sharedStore] createSong]; 
song1.songName = @"Song 1";
song1.achievedPoints = 0;

everything works, however once I try to set the achievedPoints variable to something else than 0 I get an EXC_BAD_ACCESS.

This is what the createSong method does:

- (Song *)createSong {
    double order;
    if ([allSongs count] == 0) {
        order = 1.0;
    } else {
        order = [[allSongs lastObject] orderingValue] + 1.0;
    }

    Song *p = [NSEntityDescription insertNewObjectForEntityForName:@"Song" inManagedObjectContext:context];

    [p setOrderingValue:order];
    [allSongs addObject:p];
    return p;
}

I have no idea why getting the value and setting it to 0 works but anything else than zero crashes the program. Any help is highly appreciated.

Answer 1

This has happened to me once before. I don’t know exactly which settings gets messed up, but there is a setting in your managed object model, I think, that controls whether or not the class should use primitive values (int, float, etc) or object values (NSNumber *, etc) to set its values. If this gets messed up, and you think you are setting a primitive when you are actually setting an object the following will happen:

//song1.achievedPoints = 0;
song1.achievedPoints = (NSNumber *)0x00000000; 
//This is OK because it is the same as nil

//song1.achievedPoints = 1;
song1.achievedPoints = (NSNumber *)0x00000001; //You can see why this is bad!

My solution was to regenerate the class via the Create NSManagedObject Subclass template, making sure that Use Scalar Values for Primitives was checked.