Dave Birdsall Pikuseru
douglashill
/ covariance.m
Last active
November 25, 2016 14:53
A quick look at variance with Objective-C generics. `NSSet` is covariant on its `ObjectType`, while `NSHashTable` is invariant. Contravariance is also supported.
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| @import Foundation; | |
| @interface ContravariantCollection<__contravariant ObjectType> : NSObject | |
| @end | |
| @implementation ContravariantCollection | |
| @end | |
| void stringSetThing(NSSet<NSString *> *set) { | |
| } |