ios / xcode / objective-c：有什么方法可以链接到核心数据驱动页面中的其他视图控制器？

Question

I want to do something in app that is standard and trivial on web but may not be possible in IOS. Just wondering if there is a way I haven't thought of.

Core data model based on mysql data scheme is:

entity/table of cuisine types ie italian, chinese, indian etc. entity/table of restaurants entity/table of cuisine linked to restaurants

On web, there is a page of cuisines pulled from cuisines table. You can click on cuisine and it shows restaurants associated with that cuisine pulled from cuisine-restaurants table. Then you can click on the restaurant and go to the restaurant detail page pulled from restaurants table. Routine stuff for web.

For app, I have a view controller of cuisines that pulls from the cuisines entity. However, when you click on cuisine, I can't think of a way to get a list of restaurants associated with the cuisine from the cuisine-restaurant entity as you are now pulling from a different entity.

If I could get this list of restaurants, I imagine I could get the restaurant detail using standard master detail patter.

However, I can't figure out middle step or how to put it all together.

Does anyone know of a way to do this in core data/objective-c or can recommend a tutorial that does this in core data?

Thanks in advance for any suggestions.

Answer 1

The usual approach in Core Data would be to have a relationship from a Cuisine entity to a Restaurant entity. In code this would look like a set of related objects. Any time you have an instance of Cuisine , you'd just ask it for the value of its restaurants property. In other words, once you have the cuisines, you'd already have everything you need to get a full list of restaurants for each one. You'd just get the collection of restaurants and then hand that off to the view controller that can display them.

In the model editor it would look something like this:

In code, once you had an instance of Cuisine , getting the restaurants for that cuisine would just be:

NSSet *restaurants = cuisine.restaurants;

Or if you're not using custom NSManagedObject subclasses,

NSSet *restaurants = [cuisine valueForKey:@"restaurants"];