Xcode 8 :function types cannot have argument label breaking my build

UKDataGeek picture UKDataGeek · Sep 21, 2016 · Viewed 19.1k times · Source

It seems that for some reason Swift have chosen to make coding in it less readable by forcing users to remove completion handler parameter labels. I have read the Swift discussion and still think it's a mistake. At least they could have made it optional.

When building using Xcode 8 - is there a way to force the compiler to use Swift 2.3 so I don't get these errors anymore? I have updated the option to use legacy Swift (under build settings) legacy support in xcode but I still seem to get this error:

Function types cannot have argument label 'isloggedIn'; use '_' instead

error Xcode 8

How can I keep my labels in my completion handlers?

Answer

Crashalot picture Crashalot · Sep 27, 2016

The Swift designers decided to prohibit argument labels for function types.

The reasoning is explained here: https://github.com/apple/swift-evolution/blob/master/proposals/0111-remove-arg-label-type-significance.md

This is a frustrating and questionable choice, as prohibiting argument labels makes it much easier to incorrectly invoke closures, which seems more important than simplifying the language's type system.

Usability > ideology.