用于iOS聚合的CoreData或SQLite

Question

I have an iPhone app that requires local storage.

My initial thought was to use core data, which is fine for a most of the app, however a major chunk is using aggregations on the data. In SQLite this is the standard use of MIN, MAX, AVG, GROUP_BY etc.

But core data doesn't implement these very well, as it is primarily for object graph management. Would it matter if I did the calculations in Obj-C once loaded from CoreData, or should I stick with SQLite and forgo the usefulness of the CoreData system other parts?

The collections for aggregation over are not huge (max 100 objects say). I need to do things like distributions.

I know there is no concrete answer here, just would like some second options. Thanks

Answer 1

I use both Core Data and FMDB (an Objective-C wrapper around SQLite) in my app, and it works fine. Core Data adds a "Z" in front of your table and field names, so for example, if you have a Core Data entity called Contacts, you can do a query such as SELECT COUNT(*) FROM ZCONTACTS and it will give you back the results of the SQL query.

Answer 2

就个人而言，只要“大多数应用程序”不使用MIN，MAX，AVG，我就会留在CoreData中......因为那时“大多数应用程序”仍然与SQLite相比仍然很多。

Answer 3

You could use both. First aggregate your data, select the id and use

NSManagedObjectContext context; // Get it some how
NSManagedObject *obj = [context objectWithID:objectID];

to get the corresponding managed object.