How to represent Core Data optional Scalars (Bool/Int/Double/Float) in Swift?

Question

(first noticed on: Xcode 8.2.1, iOS 10, Swift 3) (still present as of: Xcode 9 beta 3, iOS11, Swift 4)

We all know that the Core Data concept of o

Answer 1

I see the same thing, and I consider it to be a bug. It's not documented anywhere that I can find. Apparently Core Data is applying Objective-C style assumptions here, where a boolean defaults to NO, and an integer defaults to 0. The Core Data/Swift interface has some rough edges, and this is one I hadn't considered before.

It's a good find but I think you're stuck with it until Apple addresses it. You already know the best workarounds, which I agree aren't great. I recommend filing a bug.

Answer 2

If you end up here with this:

@NSManaged var boolAttribute: Bool

and it is not being seen in Objective-C, and you have already disabled "Optional" and enabled "Use Scalar Type" on those attributes, then do yourself a favour.

Double check you have imported your Swift bridging header into that Objective-C file.

I did not and, well, I was most of the way to changing my Bools to NSNumbers before smacking my head and realising how foolish I had been.

Answer 3

I could use Objective-C types to manage these cases. In these cases, for scalars types, you can use NSNumber.

 @NSManaged public var myDouble: NSNumber?

In the model myDouble is an optional double with nil value by default.

To get the real value you only need to use:

myEntity.myDouble?.doubleValue

Answer 4

This happens because Objective-C scalar types do not have a notion of nil value. Source: handling-core-data-optional-scalar-attributes