In this example, `kTISPropertyUnicodeKeyLayoutData` is already a `CFStringRef` (a.k.a. `NSString*`).
The type `_NSString` from `mred/private/wx/cocoa/types` (or, better for most purposes, from `ffi/unsafe/nsstring`) is really a pointer to an `_NSString`; it just gets tedious to put `Ref` or `-pointer` everywhere. I'll fix the docs for `_NSString`. At Fri, 2 Jan 2015 14:37:20 +0100, Jens Axel Søgaard wrote: > What is the best way of creating a reference to an existing Objective C > object? > > Concretely given an CFString how do I get an CFStringRef (aka pointer > to a CFStringRef). > > /Jens Axel > > > #lang racket > (require ffi/unsafe/objc) > (require ffi/unsafe > ffi/unsafe/objc > ffi/unsafe/define > mred/private/wx/cocoa/types) > > ;; Import CoreFoundation > (define cf-lib > (case (system-type) > [(macosx) (ffi-lib > "/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation")] > [else #f])) > > (define-ffi-definer define-cf cf-lib #:default-make-fail make-not-available) > > ;; CFString and NSString are equivalent (?) > (import-class NSString) > (define _CFString _NSString) > > ;; Create an CFString > (define kTISPropertyUnicodeKeyLayoutData > (tell (tell NSString alloc) > initWithUTF8String: #:type _string > "kTISPropertyUnicodeKeyLayoutData")) > > ;; The API needs an CFStringRef that is a pointer to CFString. > (define _CFStringRef (_ptr i _CFString)) > > > (define reference-to-kTISPropertyUnicodeKeyLayoutData '???) > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
