Core Data NSTimeInterval using an accessor directly is buggy

Question

I\'m setting an NSTimeInterval using setValueForKey within an NSManagedObject Subclass, the value gets set correctly, and is also correct when it is retrieved using valueFor

Answer 1

A scalar property of type NSTimeInterval for a Core Data Date property represents the time in seconds since the reference date Jan 1, 2001. The Core Data generated accessor methods transparently convert between NSTimeInterval and NSDate.

Therefore you set a value using the scalar accessor with

obj.dateLastSynced = date.timeIntervalSinceReferenceDate

and you retrieve the value with

let date = NSDate(timeIntervalSinceReferenceDate: obj.dateLastSynced)

This gives the same results as the Key-Value Coding methods

// Set:
obj.setValueForKey(date, "dateLastSynced")
// Get:
let date = obj.valueForKey("dateLastSynced")