wrapping objective c objects from javascript

[Phillip Johnson]

I'm working on an experiment where I'm trying to nest a framework instances in nodobjc in a NSView returned from electron. Is there a way to cast these pointers so that I can use the functions in this object?

var myView = mainWindow.getNativeWindowHandle() //returns pointer to NSView
console.log(myView);

output: Buffer@0x7ff8a2ff6300 c0 2d 06 a5 f8 7f 00 00

[Nathan Rajlich]

Well, it's not great, but you can do:

require('nodobjc/lib/core').wrapValue(buffer, '@');

Pull requests appreciated to add perhaps a Class#cast(pointer) function or something more user-friendly for this use-case.

[Phillip Johnson]

First off, thank you so much for the prompt response... and I guess I should apologize because I'm new to objective c (my experience lies mostly in c#, c++ and starting on javascript).

this would return an "@"? I'm not exactly sure what that means. Would this take the buffer and cast it as an id? Any thoughts on how i'd use NSView based on that?

[Nathan Rajlich]

See https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtTypeEncodings.html.

@ means an generic "id", which you can send arbitrary messages to. Essentially, the result of the wrapValue() call is the NSView instance. Invoke it as a function to send NSView instance method messages to it.

var nsview = ….wrapValue(…);
nsview('setFrameSize', { width: 100, height: 100 });

[Phillip Johnson]

i didn't get terribly far. I just crashes out right when I try to call any functions from nsview, it doesn't even catch the exception.

var $ = require ('nodobjc');
var $C = require ('nodobjc/lib/core');
.........
var myView = mainWindow.getNativeWindowHandle();
console.log(JSON.stringify(myView));
console.log(typeof myView);
var nsview = $C.wrapValue(myView, '@');
try {
nsview('setFrameSize', { width: 100, height: 100 });
} catch(err){
console.log(err);
}

/////
// output:
// {"type":"Buffer","data":[48,4,19,156,229,127,0,0]}
// object

[Phillip Johnson]

fixed by making this change...
var nsview = $C.wrapValue(myView, '@');

to...

var nsview = $C.wrapValue(myView.readPointer(0), '@');

[Borys Korobeinikov]

Could you share your working code here? i'm trying to do the same thing but chrome window just crash when calling 'setFrameSize' or any other method from nsview object.