NSCopying Protocol Not Working

Question

I am trying to copy an object, and I've implemented the NSCopying protocol, which looks like this:

#MyActivity.h
@interface MyActivity : MyModel <NSCopying>
{
    NSInteger activityId;
    NSInteger userId;
    NSInteger checkinId;
    NSString *status;
    NSString *dateCreated;
    NSString *dateModified;
    NSString *dateStart;
    NSString *dateEnd;
    NSString *activityDescription;
    NSString *name;
    NSString *type;
    NSString *repeat;
    NSString *routineName;
    NSString *startTimezone;
    NSString *endTimezone;
    GUILocation *location;
}

@property NSInteger activityId;
@property NSInteger userId;
@property NSInteger checkinId;

@property (nonatomic, strong) NSString *status;
@property (nonatomic, strong) NSString *dateCreated;
@property (nonatomic, strong) NSString *dateModified;
@property (nonatomic, strong) NSString *dateStart;
@property (nonatomic, strong) NSString *dateEnd;
@property (nonatomic, strong) NSString *activityDescription;
@property (nonatomic, strong) NSString *name;
@property (nonatomic, strong) NSString *type;
@property (nonatomic, strong) NSString *repeat;
@property (nonatomic, strong) NSString *routineName;
@property (nonatomic, strong) NSString *startTimezone;
@property (nonatomic, strong) NSString *endTimezone;

@property (nonatomic, strong) MyLocation *location;

-(id)copyWithZone:(NSZone *)zone;
...

This is what my implementation file looks like:

#MyActivity.m
...
-(id)copyWithZone:(NSZone *) zone
{
    GUIActivity* copyActivity        = [super copyWithZone:zone];
    copyActivity.activityId          = self.activityId;
    copyActivity.userId              = self.userId;
    copyActivity.checkinId           = self.checkinId;
    copyActivity.status              = self.status;
    copyActivity.dateCreated         = self.dateCreated;
    copyActivity.dateModified        = self.dateModified;
    copyActivity.dateStart           = self.dateStart;
    copyActivity.dateEnd             = self.dateEnd;
    copyActivity.activityDescription = self.activityDescription;
    copyActivity.name                = self.name;
    copyActivity.type                = self.type;
    copyActivity.repeat              = self.repeat;
    copyActivity.routineName         = self.routineName;
    copyActivity.startTimezone       = self.startTimezone;
    copyActivity.endTimezone         = self.endTimezone;
    copyActivity.location            = [self.location copyWithZone:zone];


    return copyActivity;
}
...

When I attempt to copy by implementing this method:

- (void)addActivity:(MyActivity *)activity
          toResults:(NSMutableArray *)results
           withDate:(NSDate *)date
{
    MyActivity *actNow     = [activity copy];
    actNow.dateStart       = [NSDate stringFromDate:date];
    [results addObject:actNow];
}

I am still getting the error:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[RLMAccessor_v0_MyActivity copyWithZone:]: unrecognized selector sent to instance 0x7fe5e0c2c0a0'

The class MyActivity is a subclass of RLMObject , so I'm not sure if that has anything to do with the issue. Can someone point me in the right direction?

Answer 1

Realm internally overrides the accessors for the properties it manages, so it's not possible to make it conform to NSCopying in the traditional sense.

If you want to perform a full deep copy on an RLMObject , the Realm-JSON library actually provides a way to do this :

- (instancetype)deepCopy {
    RLMObject *object = [[NSClassFromString(self.objectSchema.className) alloc] init];

    for (RLMProperty *property in self.objectSchema.properties) {

        if (property.type == RLMPropertyTypeArray) {
            RLMArray *thisArray = [self valueForKeyPath:property.name];
            RLMArray *newArray = [object valueForKeyPath:property.name];

            for (RLMObject *currentObject in thisArray) {
                [newArray addObject:[currentObject deepCopy]];
            }

        }
        else if (property.type == RLMPropertyTypeObject) {
            RLMObject *value = [self valueForKeyPath:property.name];
            [object setValue:[value deepCopy] forKeyPath:property.name];
        }
        else {
            id value = [self valueForKeyPath:property.name];
            [object setValue:value forKeyPath:property.name];
        }
    }

    return object;
}