[MacRuby-devel] Accessing bytes within NSData

[Brian Chapados]

Hi Pete,

Since you have an NSData object, you should be able to convert it to a
String (NSString) and then use unpack.  For example:

socket_port = NSSocketPort.alloc.initWithTCPPort(11111)
addr = socket_port.address
addr_str = NSString.alloc.initWithData(addr,
encoding:NSString.defaultCStringEncoding)
port = addr_str.unpack("nn")[1]  # seems to work - not sure what this should be

I suppose the other alternative would be to add some methods to the
Pointer class making it possible to set the type of a returned
Pointer.

Brian

On Sun, Mar 22, 2009 at 3:18 PM, Pete Yandell <pete at notahat.com> wrote:
> I'd like to use something like Ruby's String#unpack to pull some info out of
> an NSData, but I'm stumped as to how to do it.
>
> NSData.bytes returns a Pointer object, but trying to use [] to dereference
> it gives me:
>
>        ArgumentError: can't convert C/Objective-C value `0x800059800' of
> type `?_?' to Ruby object
>
> I've done a lot of digging around, reading of forum posts, playing
> (unsuccessfully) with BridgeSupport, etc., but it hasn't got me any closer.
> Any hints?
>
> The broader context is that I'm trying to extract the TCP port number from
> an NSSocketPort. NSSocketPort's address method returns an NSData, which
> should contain a sockaddr_in, out of which I should be able to pull the
> port.
>
> Thanks,
>
> Pete Yandell
> http://notahat.com/
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