Another workaround would be
public init(uti: String) {
switch uti.lowercased() {
case String(kUTTypeText):
self = .text
default:
self = .unknown
}
}
because there is a `String(_ cocoaString: NSString)` initializer in Foundation.
Regards, Martin
> Am 05.12.2017 um 10:09 schrieb Dennis Weissmann via swift-users
> <swift-users@swift.org>:
>
> Hi swift-users,
>
> I have found another weird behavior (IMO) and wanted to ask for the right way
> to handle this:
>
> Imagine I want to switch over a Swift string which contains a UTI to map that
> UTI to an enum.
>
> (A playground is attached for you to easily reproduce, this is tested with
> Xcode 9.1's included toolchain, also happens in projects)
>
> I would expect the following to work:
>
> import MobileCoreServices
>
> enum MimeType {
>
> case text
> case unknown
>
> public init(uti: String) {
> // Source:
> https://developer.apple.com/library/content/documentation/Miscellaneous/Reference/UTIRef/Articles/System-DeclaredUniformTypeIdentifiers.html
> switch uti.lowercased() {
> case kUTTypeText as String:
> self = .text
> default:
> self = .unknown
> }
> }
>
> }
>
> The error I get here is
>
> warning: UTITest.playground:8:26: warning: 'as' test is always true
> case kUTTypeText as String:
> ^
>
> error: UTITest.playground:8:14: error: expression pattern of type 'CFString'
> cannot match values of type 'String'
> case kUTTypeText as String:
> ^~~~~~~~~~~
> ^~~~~~~~~~~
> The only way I found to resolve this is to also import Foundation (which
> makes sense but is not really obvious).
>
> Alright, that gives me this:
>
> import MobileCoreServices
> import Foundation
>
> enum MimeType {
>
> case text
> case unknown
>
> public init(uti: String) {
> // Source:
> https://developer.apple.com/library/content/documentation/Miscellaneous/Reference/UTIRef/Articles/System-DeclaredUniformTypeIdentifiers.html
> switch uti.lowercased() {
> case kUTTypeText as String:
> self = .text
> default:
> self = .unknown
> }
> }
>
> }
>
> warning: UTITest.playground:8:26: warning: 'as' test is always true
> case kUTTypeText as String:
> ^
>
> error: UTITest.playground:8:14: error: 'CFString' is not implicitly
> convertible to 'String'; did you mean to use 'as' to explicitly convert?
> case kUTTypeText as String:
> ^
> as String
>
>
> Uhm, okay? So let's do that:
>
> enum MimeType {
>
> case text
> case unknown
>
> public init(uti: String) {
> // Source:
> https://developer.apple.com/library/content/documentation/Miscellaneous/Reference/UTIRef/Articles/System-DeclaredUniformTypeIdentifiers.html
> switch uti.lowercased() {
> case kUTTypeText as String as String:
> self = .text
> default:
> self = .unknown
> }
> }
>
> }
>
> As weird as it looks, it works ... My question is: Is this behavior intended?
>
> Thanks!
>
> - Dennis
> <UTITest.playground>
> _______________________________________________
> swift-users mailing list
> swift-users@swift.org
> https://lists.swift.org/mailman/listinfo/swift-users
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