re: Core Data Predicate Builder - comparing dates
re: Core Data Predicate Builder - comparing dates
- Subject: re: Core Data Predicate Builder - comparing dates
- From: Ben Trumbull <email@hidden>
- Date: Sat, 29 Aug 2009 17:35:33 -0700
I have a Core Data entity that has a dateCreated and a dateModified -
both NSDates in the object files.
I'd like to construct a predicate that will retrieve all records where
a record's dateModified is greater than that record's dateCreated.
Its deceptively easy to setup something that looks like it should work
using 'Control-click' and 'Key' in the predicate builder in XCode.
But when I run queries it doesn't appear to yield the right results.
My thinking is that the comparison operators don't properly evaluate
dates (am I wrong?)
Comparison operators work just fine on dates, although == and != are
fragile since NSDates are double time stamps, and floating point
numbers have odd == behavior.
What does the predicate look like ? How is it not working ? What
does SQL logging show ?
So dropping back to code - how would I write this predicate in code?
[NSPredicate predicateWithFormat:@"dateModified > dateCreated"]
- Ben
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