I am able to save ratatouilleMutableDic without issue. But ratatouilleDic throws exception:
// 'NSUnknownKeyException', reason: '[<__NSDictionaryI 0xa870630> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key id.'

See test code below:
NSMutableDictionary *ratatouilleMutableDic = [@

{ @"title" : @"Ratatouille", @"description" :recipeWriting}

mutableCopy];
[store save:ratatouilleMutableDic error:nil];

NSDictionary *ratatouilleDic = @

{ @"title" : @"Ratatouille", @"description" :recipeWriting}

;
[store save:ratatouilleDic error:nil];

Expected behavior: should accept both without issue.