[swift-users] #selector() in Swift

[Mohit Athwani]

Hi Alex,

Thanks for the update!

Cheers!


--
Mohit Athwani
http://about.me/mohitathwani

On Aug 10, 2017, 2:56 AM -0700, Alex Blewitt <alblue at apple.com>, wrote:
> > On 10 Aug 2017, at 07:04, Mohit Athwani via swift-users <swift-users at swift.org> wrote:
> >
> > With closures being first class citizens in Swift and the ability of closures to be able to capture scope, it seems a little archaic to me that the #selector() feature exists in Swift.
> >
> > For example, why does
> > func addTarget(_ target: Any?, action: Selector, for controlEvents: UIControlEvents)
> >
> > have a Selector type for action. Why can’t action be defined to be a closure  for example:
> > addTarget(_ target: Any?, action: (sender: UIControl?, forEvent event:UIEvent?) -> Void, for controlEvents: UIControlEvents)
> >
> > What do you guys think?
>
> Selectors have been around since the start of the Objective-C platform, before either macOS or iOS existed. Blocks weren't added into macOS until relatively recently (from iOS 4 https://en.wikipedia.org/wiki/Blocks_(C_language_extension) if you're interested).
>
> So many of the APIs that predated the introduction of blocks worked by having a selector that could be called back on a target, and these APIs are still present today in current releases of macOS and iOS.
>
> The Swift based API is purely there because there are some APIs that aren't capable of taking a block, and hence aren't capable of taking a Swift closure.
>
> Alex
>
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