SelectVerticallyCenteredColon.m

- (void)drawRect:(NSRect)dirtyRect {
	CGContextRef context = [[NSGraphicsContext currentContext] graphicsPort];
	CGContextSetTextMatrix(context, CGAffineTransformIdentity);

	CTFontRef font = CTFontCreateUIFontForLanguage(kCTFontUIFontSystem, 12.0, NULL);
	
	// Use this to find out the feature identifiers we use below.
	CFTypeRef features = CTFontCopyAttribute(font, kCTFontFeaturesAttribute);
	NSLog(@"%@", features);
	CFRelease(features);
	
	NSDictionary* attributes =
		@{ (id)kCTFontFeatureSettingsAttribute: @[ @{ (id)kCTFontFeatureTypeIdentifierKey: @35, (id)kCTFontFeatureSelectorIdentifierKey: @6 }  ] };
	CTFontDescriptorRef desc = CTFontDescriptorCreateWithAttributes((CFDictionaryRef)attributes);
	CTFontRef fontWithCenteredColon = CTFontCreateCopyWithAttributes(font, 12.0, NULL, desc);
	CFRelease(desc);
	CFRelease(font);

	NSAttributedString* attrString = [[NSAttributedString alloc] initWithString:@"Hello:World" attributes:@{ (id)kCTFontAttributeName: (__bridge id)fontWithCenteredColon }];
	CTLineRef line = CTLineCreateWithAttributedString((CFAttributedStringRef)attrString);
	CFRelease(fontWithCenteredColon);

	CGContextSetTextPosition(context, 50, 50);
	CTLineDraw(line, context);
}