Exporting a QR to vector NSImage & CGPDFContextCreate - macOS ObjC - objective-c

Question

I've been trying to figure out how to export my QR codes on my little project as a vector.
I start from qrImageForString function which generates the image initially, and does so as a bitmap.
The main two lines in question are:
CGContextRef ctx = CGBitmapContextCreate(0, size, size, 8, size * 4, colorSpace,kCGImageAlphaPremultipliedLast);
CGImageRef qrCGImage = CGBitmapContextCreateImage(ctx);
For the first one I think this may be a replacement:
NSRect rect = CGRectMake(0.0, 0.0, 750.0, 750.0);
CGContextRef ctx = CGPDFContextCreate(dataConsumer, &rect, NULL);
However I'm not sure how to replace the second line to make it a vector.
Full function is:
+ (NSImage *)qrImageForString:(NSString *)string imageSize:(CGFloat)size {
if (![string length]) {
return nil;
}
int str1;
QRcode *code = QRcode_encodeString([string UTF8String], 0, str1, QR_MODE_8, 1);
// create context
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef ctx = CGBitmapContextCreate(0, size, size, 8, size * 4, colorSpace, kCGImageAlphaPremultipliedLast);
NSRect rect = CGRectMake(0.0, 0.0, 750.0, 750.0);
NSMutableData* outputData = [[NSMutableData alloc] init];
CGDataConsumerRef dataConsumer = CGDataConsumerCreateWithCFData((CFMutableDataRef)outputData);
CGAffineTransform translateTransform = CGAffineTransformMakeTranslation(0, -size);
CGAffineTransform scaleTransform = CGAffineTransformMakeScale(1, -1);
CGContextConcatCTM(ctx, CGAffineTransformConcat(translateTransform, scaleTransform));
// draw QR on this context
[MainClass drawQRCode:code context:ctx size:size];
// get image
CGImageRef qrCGImage = CGBitmapContextCreateImage(ctx);
NSImage *qrImage = [[NSImage alloc] initWithCGImage:qrCGImage size:NSZeroSize];
// some releases
CGContextRelease(ctx);
CGImageRelease(qrCGImage);
CGColorSpaceRelease(colorSpace);
QRcode_free(code);
return qrImage;
}

Answer 1

Copied from How to make dataWithEPSInsideRect vector rather than bitmap in vector format?: Create an offscreen view, set up the draw method of the view to include your graphic and then use NSView's dataWithEPSInsideRect: method.
I made mdDrawQRCode:context:size:fillColor: an instance method of the view but it can be a method of different class. The view:
#interface MyView : NSView
#property (strong) NSString *qrString;
#end
#implementation MyView
- (void)drawRect:(NSRect)dirtyRect {
[super drawRect:dirtyRect];
if (!self.qrString)
return;
CGContextRef cgContext = [[NSGraphicsContext currentContext] CGContext];
CGContextSaveGState(cgContext);
QRcode *code = QRcode_encodeString([self.qrString UTF8String], 0, QR_ECLEVEL_L, QR_MODE_8, 1);
[self mdDrawQRCode:code context:cgContext size:self.bounds.size.width fillColor:[NSColor blackColor]];
QRcode_free(code);
CGContextRestoreGState(cgContext);
}
#end
Use the view like:
MyView *myView = [[MyView alloc] initWithFrame:NSMakeRect(0, 0, 100.0, 100.0)];
myView.qrString = #"Hello World!";
NSData *data = [myView dataWithEPSInsideRect:myView.bounds];