I have saved data into db using CoreData. I need to fetch data from my table in same order that it was saved. Inside table it is ordered by Z_PK - hidded CoreData key. How can I create such sort descriptor. If I use fetch request without sort descriptors my data objects have wrong order.
Anything not exposed to you by the Core Data framework is an implementation detail. The fact that Z_PK exists, and currently suits your purposes, cannot be relied upon.
If creation/save order is important to your model, then it should be included in your model. There's really nothing else to it.
There is no proper method in core data framework to sort object by primary key, but I think we can use objectID as a the primary key and sort by objectID. ObjectID for a particular object would always increase.. thus you can use below method
/*!
@param <NSManagedObject> array
@return <NSManagedObject> sortedarray
*/
+ (NSArray *) sortManagedObjectArrayByObjectID:(NSArray *) array {
NSArray *compareResult = [array sortedArrayUsingComparator:^NSComparisonResult(NSManagedObject *obj1, NSManagedObject *obj2) {
NSString *s = [obj1.objectID.URIRepresentation lastPathComponent];
NSString *r = [obj2.objectID.URIRepresentation lastPathComponent];
return [s compare:r];
}];
return compareResult;
}
Hope this would help
Use a sort descriptor with self as the sort key. The underlying SQL will have ORDER BY t0.Z_PK.
来源：https://stackoverflow.com/questions/12949540/ios-get-objects-from-coredata-sorted-by-primary-key