> On Feb 13, 2017, at 9:33 PM, Jeff Kelley via swift-evolution > <swift-evolution@swift.org> wrote: > > Hi all, > > I don’t have a formal proposal written up yet, but in my continued > quest to make better-annotated Objective-C code, I had an idea for bridging > nil with primitives. Since in Objective-C we often use constant values to > represent invalid values or nil, the most obvious being NSNotFound, could we > use that as a shorthand for nil? Something like this for NSArray: > > - (NSUInteger NS_SWIFT_NIL(NSNotFound))indexOfObject:(ObjectType)anObject; > > This is a little verbose, so it could also work with a typedef: > > typedef NSUInteger NS_SWIFT_NIL(NSNotFound) NSArrayIndex; > - (NSArrayIndex)indexOfObject:(ObjectType)anObject; > > This would change the existing Swift interface to return an Int? > instead of an Int. I see this as working both ways—converting these values to > nil when returning from Objective-C to Swift, and sending these values > instead of nil when Swift calls into Objective-C code. > > Is this worth writing up a proposal for? Is another, better method > already in someone’s mind?
What happens if code on the Swift side sets the property’s value to the sentinel? Charles
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