5.16 Cocoa Foundation
The ffi/unsafe/nsalloc and ffi/unsafe/nsstring libraries provide basic facilities for working with Cocoa and/or Mac OS Foundation libraries (usually along with ffi/objc).
5.16.1 Strings
| (require ffi/unsafe/nsstring) | package: base |
value
_NSString : ctype?
A type that converts between Racket strings and
NSString* (a.k.a. CFStringRef)
values. That is, use _NSString as a type for a foreign-function
NSString* argument or result.
The _NSString conversion keeps a weak mapping from Racket strings to converted strings, so that converting the same string (in the equal? sense) multiple times may avoid allocating multiple NSString objects.
5.16.2 Allocation Pools
| (require ffi/unsafe/nsalloc) | package: base |
Calling any Foundation API that
allocates requires an NSAutoreleasePool installed. The
ffi/unsafe/nsalloc library provides a function and
shorthand syntactic form for setting up such a context. (The
_NSString type creates an autorelease pool implicitly while
converting from/to a Racket string, however.)
procedure
(call-with-autorelease thunk) → any
thunk : (-> any)
Calls thunk in atomic mode and with a fresh
NSAutoreleasePool that is released after thunk
returns.
syntax
(with-autorelease expr)