CODEWITHSUNDEEP
core-dataswift2xcode7nsset
FranMowinckel
FranMowinckel

Reputation: 4343

Using typed Set in CoreData NSManaged relationship

When you create a managed object relationship (i.e. one to many), and then you create a NSManagedObject subclass, you would code that relationship like:

@NSManaged var dogs: NSSet

But I found out that instead you can write:

@NSManaged var dogs: Set<Dog>

Which in my opinion, it is much more convenient because you have a typed Set and casting in Swift is quite verbose.

Edited: Actually, I have found out that you can use the insert and remove method of the Set so it's even easier.

I know about Swift automatic bridging from some Foundation classes to Swift classes (i.e. NSArray to Array and NSSet to Set).

But I haven't found about using Swift typed Sets for implementing Core Data Managed object subclasses in the docs or in any other tutorial and I wonder why.

I'm using Xcode 7.2 and Swift 2 and it works fine in my project. Does it also work for someone else? some Apple doc somewhere? or is it a bad idea for some reason I'm missing?

Upvotes: 4

Views: 864

Answers (1)

Mundi
Mundi

Reputation: 80273

Yes, this is common practice among many developers as far as I know.

In fact, the generated NSManagedObject subclasses are not at all perfect when it comes to the generated types. For examples, primitives still have problems, and NSNumber sometimes bridges successfully to Bool, sometimes not. Quite often I had to modify the optional state as well.

If you leave the preset NSSet, you can still cast to Set<Type> which is what I did before getting into the habit of changing the generated subclasses' to-many properties to typed sets.

Upvotes: 3

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