If you are not interested in the details of Mongolian but just want a quick answer about using and converting Unicode values in Swift, then skip down to the first part of the [accepted answer][1].

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#Background

I want to render Unicode text for [traditional Mongolian to be used in iOS apps][2]. The better and long term solution is to use an [AAT smart font][3] that would render this complex script. ([Such fonts do exist][4] but their license does not allow modification and non-personal use.) However, since I have never made a font, let alone all of the rendering logic for an AAT font, I just plan to do the rendering myself in Swift for now. Maybe at some later date I can learn to make a smart font. 

Externally I will use Unicode text, but internally (for display in a `UITextView`) I will convert the Unicode to individual glyphs that are stored in a dumb font (coded with Unicode [PUA][5] values). So my rendering engine needs to convert Mongolian Unicode values (range: U+1820 to U+1842) to glyph values stored in the PUA (range: U+E360 to U+E5CF). Anyway, this is my plan since it is [what I did in Java in the past][6], but maybe I need to change my whole way of thinking.

#Example

The following image shows *su* written twice in Mongolian using two different forms for the letter *u* (in red). (Mongolian is written vertically with letters being connected like cursive letters in English.) 

![enter image description here][7]

In Unicode these two strings would be expressed as 

    var suForm1: String = &quot;\u{1830}\u{1826}&quot;
    var suForm2: String = &quot;\u{1830}\u{1826}\u{180B}&quot;

The Free Variation Selector (U+180B) in `suForm2` is recognized (correctly) by Swift `String` to be a unit with the *u* (U+1826) that precedes it. It is considered by Swift to be a single character, an extended grapheme cluster. However, for the purposes of doing the rendering myself, I need to differentiate *u* (U+1826) and FVS1 (U+180B) as two distinct UTF-16 code points.

For internal display purposes, I would convert the above Unicode strings to the following rendered glyph strings:

    suForm1 = &quot;\u{E46F}\u{E3BA}&quot; 
    suForm2 = &quot;\u{E46F}\u{E3BB}&quot;

#Question

I have been playing around with Swift `String` and `Character`. There are a lot of convenient things about them, but since in my particular case I deal exclusively with UTF-16 code units, I wonder if I should be using the old `NSString` rather than Swift&#39;s `String`. I realize that I can use `String.utf16` to get UTF-16 code points, but [the conversion back to `String` isn&#39;t very nice][8].

Would it be better to stick with [`String`][9] and [`Character`][10] or should I use [`NSString`][11] and [`unichar`][12]?

#What I have read

- [Strings and Characters documentation][13]
- [Strings in Swift][14]
- [NSString and Unicode][15]

*Updates to this question have been hidden in order to clean the page up. See the edit history.*

  [1]: https://stackoverflow.com/a/31483262/3681880
  [2]: https://stackoverflow.com/questions/28544714/how-do-you-make-a-vertical-text-uilabel-and-uitextview-for-ios-in-swift
  [3]: https://en.wikipedia.org/wiki/Apple_Advanced_Typography
  [4]: http://www.mongolfont.com/en/font/mnglwhiteaat.html
  [5]: https://en.wikipedia.org/wiki/Private_Use_Areas
  [6]: https://github.com/suragch/Chimee/blob/master/app/src/main/java/net/studymongolian/chimee/MongolUnicodeRenderer.java
  [7]: http://i.stack.imgur.com/xtEJJ.png
  [8]: https://stackoverflow.com/questions/24542170/is-there-a-way-to-create-a-string-from-utf16-array-in-swift
  [9]: https://developer.apple.com/library/prerelease/ios/documentation/Swift/Reference/Swift_String_Structure/index.html
  [10]: https://developer.apple.com/library/prerelease/ios/documentation/Swift/Reference/Swift_Character_Structure/index.html
  [11]: https://developer.apple.com/library/ios/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/index.html
  [12]: https://developer.apple.com/library/ios/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/index.html#//apple_ref/c/tdef/unichar
  [13]: https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/StringsAndCharacters.html
  [14]: http://oleb.net/blog/2014/07/swift-strings/
  [15]: http://www.objc.io/issues/9-strings/unicode/
  [16]: https://stackoverflow.com/a/31327086/3681880
  [17]: https://stackoverflow.com/a/31026358/3681880
  [18]: https://stackoverflow.com/questions/31421054/convert-uint32-utf-32-to-string-in-swift
  [19]: https://stackoverflow.com/questions/31438210/how-to-implement-the-hashable-protocol-in-swift-for-an-int-array-a-custom-strin
  [20]: https://stackoverflow.com/questions/31421054/convert-uint32-utf-32-to-string-in-swift#comment50842032_31423768

All Mongolian Vertical-Script Solutions on Gang of Coders

Total of 1 Mongolian Vertical-Script Solutions

Working with Unicode code points in Swift