String with multilpe attributes in swift - ios

Question

I am working on an app on which i had to make the text in a UITextView bold or italic or underlined. So i came up with this solution to make the selected range from the textView bold. The same way i can make it italic and but not underlined, don't know how.
//MARK: Bold Bar Button
func boldBarButtonClicked(sender : UIBarButtonItem)
{
if let selectedTextRange = self.textView.selectedTextRange
{
let beginningOfDocument = self.textView.beginningOfDocument
let startingPoint = self.textView.offsetFromPosition(beginningOfDocument, toPosition: selectedTextRange.start)
let selectedTextLength = self.textView.offsetFromPosition(selectedTextRange.start, toPosition: selectedTextRange.end)
let dict : Dictionary<String, AnyObject> = self.textView.textStorage.attributesAtIndex(startingPoint, effectiveRange: nil)
if let currentFont = dict[NSFontAttributeName] as? UIFont
{
let fontDescriptor = currentFont.fontDescriptor()
let changedFontDescriptor = fontDescriptor.fontDescriptorWithSymbolicTraits(UIFontDescriptorSymbolicTraits.TraitBold)
let updatedFont = UIFont(descriptor: changedFontDescriptor, size: 0.0)
let updatedDict = [NSFontAttributeName : updatedFont ]
self.textView.textStorage.beginEditing()
let selectedNSRange = NSMakeRange(startingPoint, selectedTextLength)
self.textView.textStorage.setAttributes(updatedDict, range: selectedNSRange)
self.textView.textStorage.endEditing()
// Put bold tag inside letters
}
}
}
So basically when the user sees the textView i have to make the text bold. So i thought of putting the text in between bold tag just the same as html. So that i can loop through the characters and see whether there is any text which is bold or italic or underline.
Am i doing it the correct way? Finding the selected range make it bold or italic or underlined and then put the tag inside the reference string, finally passing this string to the server with tags involved, so that others can see where comes the bold or italic or underlined characters.
How this will work if the same string has multiple attributes like, if the string "alvin" has bold and italic and underline, it will be like U I B "alvin' /U /I /B (tags are same as html bold, italic, underline) correct? How can i do find these in Swift, i thought about it a lot and tired of using regular expressions and looping through the string. But could not get the proper result. Thanks in advance.