[MyObject] Custom -[willSave] and -[didSave] with changedKeys.m

@interface MyObject : NSManagedObject
@property (nonatomic, strong, nullable) NSSet *changedKeys;
@end

...

@interface MyObject

- (void)willSave {
    [super willSave];
    
    if (self.isUpdated && !self.isInserted) {
        self.changedKeys = [NSMutableSet setWithArray:self.changedValues.allKeys];
    }
}

- (void)didSave {
    if (!self.changedKeys || self.isDeleted) {
        NSMutableDictionary *userInfo = [NSMutableDictionary dictionary];
        if (self.changedKeys) {
            userInfo[@"newValue"] = self.changedKeys;
        }
        [[NSNotificationCenter defaultCenter] postNotificationName:@"kMyObjectDidSaveNotification" object:self userInfo:userInfo];
    }
    
    if (self.changedKeys && !self.inserted) {
        NSMutableDictionary *userInfo;
        if ([self.changedKeys containsObject:NSStringFromSelector(@selector(name))]) {
            userInfo = [NSMutableDictionary dictionary];
            if (self.name) {
                userInfo[@"newValue"] = self.name;
            }
            [[NSNotificationCenter defaultCenter] postNotificationName:@"kMyObjectNameDidSaveNotification" object:self userInfo:userInfo];
        }
        if ([self.changedKeys containsObject:NSStringFromSelector(@selector(createdAt))]) {
            userInfo = [NSMutableDictionary dictionary];
            userInfo[@"newValue"] = self.createdAt;
            [[NSNotificationCenter defaultCenter] postNotificationName:@"kMyObjectCreatedAtDidSaveNotification" object:self userInfo:userInfo];
        }
        
        ...
        
    }
    
    self.changedKeys = nil;
    [super didSave];
}

@end