apply_new_text_attributes.swift

class Document: NSDocument {    
	@IBAction func fontSizeChanged(sender: NSControl) {
		var newSize = CGFloat(sender.floatValue)        
		if var font = textView?.typingAttributes[NSFontAttributeName] as? NSFont {
			font = NSFontManager.sharedFontManager().convertFont(font, toSize: newSize)
			applyNewAttributes([NSFontAttributeName: font])
		}
	}
			
	func applyNewAttributes(attributes: [String: AnyObject]) {
		if let changeRanges = textView?.rangesForUserCharacterAttributeChange {            
			textView?.shouldChangeTextInRanges(changeRanges, replacementStrings: nil)
			textView?.textStorage?.beginEditing()
			for (_, value) in changeRanges.enumerate() {
				textView?.textStorage?.addAttributes(attributes, range: value.rangeValue)
			}
			textView?.textStorage?.endEditing()
			textView?.didChangeText()
		}
		
		if var typingAttributes = textView?.typingAttributes {
			typingAttributes.updateWithDictionary(attributes)
			textView?.typingAttributes = typingAttributes
		}
	}
}