I think the biggest problem we're going to face with this one is changes to 
Objective-C are out of scope for Swift Evolution. Apple tend to be the ones in 
control of the development of new Objective-C features and compatibility 
because they control the compiler.

That said, as a request to Apple for this change, I think it's a reasonable 
idea for Ints, but I'm not sure of its feasibility for other types. Could the 
API be descriptive enough to cover enough types? (Eg CGRectNull)


> On 14 Feb 2017, at 2:33 pm, Jeff Kelley via swift-evolution 
> <[email protected]> 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?
> 
> 
> Jeff Kelley
> 
> [email protected] | @SlaunchaMan | jeffkelley.org
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