intermediate_typing_attribute_binding.swift

class Document: NSDocument {
	@IBOutlet var fontSizeField: NSTextField?	
	dynamic var currentFontSize: CGFloat = 0
	
	override func windowControllerDidLoadNib(aController: NSWindowController) {
		super.windowControllerDidLoadNib(aController)
		
		fontSizeField.bind("value",
			toObject: self,
			withKeyPath: "currentFontSize",
			options: nil)         
	}   
}

extension Document: NSTextViewDelegate {
	func textViewDidChangeTypingAttributes(notification: NSNotification) {
		if let font = textView?.typingAttributes[NSFontAttributeName] as? NSFont {
			currentFontSize = font.pointSize
		}
	}
}