[swift-users] Pass Value of Variable to a Function

[Zhao Xin]

I think you messed up with `Locale` and `NSLocale`.

`Locale` is a struct in Swift 3 to replace the legacy `NSLocale`. The
latter is a class, it has an inner `structure` called `NSLocale.Key`. For
`Locale`, there is no `NSLocale.Key`. All there keys are instance
properties in `Locale`. So in your specific case,

let calendar2 =  (currentLocale as
NSLocale).object(forKey:NSLocale.Key(rawValue:propertyName))

is just almost the same as `let calendar2 = calendar1`.

If you insist on using `NSLocale.Key`, you should use `NSLocale` instead of
`Locale`.


Zhaoxin

On Wed, Sep 7, 2016 at 10:35 AM, Michael Sheaver via swift-users <
swift-users at swift.org> wrote:

> I am trying to build a table of current locale properties in code, and
> have encountered issues with trying to pass the value of a variable to a
> function:
>
> let currentLocale = Locale(identifier: "en_US")
> let calendar1 = currentLocale.calendar      // "gregorian (fixed)"
> let propertyName = "calendar"let calendar2 = currentLocale.propertyName // Error: Value of type 'Locale' has no member 'porpertyName'
>
> In the last line of code above, the instance of Locale thinks I am passing
> it "propertyName" rather than the contents of the variable "calendar".
>
> Is there any way to pass the value of propertyName ("calendar") to the
> instance of Locale? I know that in other languages, you can prepend the
> variable name like '$propertyName', and that tells it to read the value of
> the variable.
>
> I want to keep this pure Swift if possible.
> I posted this question on StackOverflow, and got the following that does
> work:
>
> let calendar2 =
>     (currentLocale as NSLocale).object(forKey:NSLocale.Key(rawValue:propertyName))
>
> It does seem odd to me that we must do some crazy Objective-C gymnastics
> to make it work. It  would seem logical to have a computed property on the
> Any type named, let's say, contentsOf that would return or pass the
> contents of the variable to the called function. For example, to use the
> original code sample above, we could use:
>
>     let calendar2 = currentLocale.propertyName.contentsOf
>
> or something similar. Thus currentLocale.propertyName would pass the
> literal "propertyName", whereas currentLocale.propertyName.contentsOf
> would pass the contents "calendar".
>
> Does anyone else agree that we need this functionality, or am I way out in
> left field on this? Or is this already possible and I haven't yet figured
> it out?
>
> Sincerest Regards,
> Michael
>
> Michael Sheaver
> msheaver at me.com
>
>
> _______________________________________________
> swift-users mailing list
> swift-users at swift.org
> https://lists.swift.org/mailman/listinfo/swift-users
>
>
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