从CoreData获取具有给定属性的相同值的对象？

Question

I want to fetch persons having the same birthday from CoreData ?

or in general if I have array of persons [Person] where Person class as follow

Person {
 var name: String
 var birthday: NSDate
}

and I want to group the persons based on birthday not birthdate, so I want [NSDate:[Person]] dictionary.

so could anyone please help me with this? Any help is appreciated.

Answer 1

NSDate is precise down to the 10th of a millisecond, so first you will have to make sure all dates have the same hours and seconds.

The best way to group in Core Data is with a NSFetchedResultsController . You can use the date as the sectionNameKeyPath and it will group automatically for you. The items in the fetched results controller can be easily accessed with index paths, very useful for table views.