One line above the text that you quoted, you can read:

> If this method returns false, the object pointer referenced by error is 
> populated with additional information.

The rationale is probably that this method was awkward to begin with. It's 
unclear to me why it was decided to return a `NSError` by reference and a bool 
that is seemingly equivalent to `error != nil`.

Félix

> Le 7 août 2016 à 10:41:32, Charles Srstka via swift-evolution 
> <[email protected]> a écrit :
> 
> -[NSURL checkResourceIsReachableAndReturnError:] has taken on several forms 
> in Swift during its development, sometimes returning a Boolean and an error 
> by reference, sometimes returning Void and using Swift’s do/try/catch system. 
> In Swift 3, though, it appears to do both, which is weird:
> 
> func checkResourceIsReachable() throws -> Bool
> 
> All the documentation has to say about this is:
> 
> "This method is currently applicable only to URLs for file system resources. 
> For other URL types, false is returned.”
> 
> It does not, however, say whether non-file URLs are the only thing that can 
> cause a return of ‘false’, so I don’t know whether I should be checking the 
> return value when checking a file URL or not. This results in having to check 
> both the return value *and* the catch block each time, which is fairly 
> awkward. I’m also not clear on why checking reachability on a non-file URL 
> can’t just return an error like it did in the past.
> 
> What’s the rationale behind this?
> 
> Charles
> 
> 
> 
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