Transliterate/transpose the characters in the NSString

Question

I want to transliterate a cyrillic string to it's closest latin equivalent. E.g. "матрешка" => "matreshka", "водка" => "vodka". So ideally I want some ready to use method on the NSString or somewhere else that already knows everything about the alphabets and can do the conversation.

But if such functionality doesn't exist in the iOS APIs then I will be totally happy with something like ruby's tr method that just replaces the characters in a string using a simple mapping specified as a parameter.

"баба".tr('абвгд', 'abvgd')

Answer 1

Either try CFStringTransform function of CFMutableString with kCFStringTransformToLatin transform identifier or make a NSString category with simple mapping.

Edited by the question poster: more specifically it should be:

NSMutableString *buffer = [@"русский язык" mutableCopy];
CFMutableStringRef bufferRef = (__bridge CFMutableStringRef)buffer;
CFStringTransform(bufferRef, NULL, kCFStringTransformToLatin, false);
NSLog(@"%@", buffer); // outputs "russkij âzyk"

Answer 2

If you don't need diacritics or accents you can call CFStringTransform(bufferRef, NULL, kCFStringTransformStripCombiningMarks, false);

Additional article: http://nshipster.com/cfstringtransform/

Answer 3

With Swift 5, String has a method called applyingTransform(_:reverse:). applyingTransform(_:reverse:) has the following declaration:

func applyingTransform(_ transform: StringTransform, reverse: Bool) -> String?

The following Playground code shows how to use applyingTransform(_:reverse:) in order to transliterate from cyrillic to latin characters:

import Foundation

let string = "матрешка"
let latinString = string.applyingTransform(StringTransform.toLatin, reverse: false)
let noDiacriticString = latinString?.applyingTransform(StringTransform.stripDiacritics, reverse: false)

print(latinString) // prints: Optional("matreška")
print(noDiacriticString) // prints: Optional("matreska")

---

As an alternative, you can use Core Foundation CFStringTransform(_:_:_:_:) function:

import Foundation

let mutableString = NSMutableString(string: "матрешка")

CFStringTransform(mutableString, nil, kCFStringTransformToLatin, false)
print(mutableString) // prints: matreška

CFStringTransform(mutableString, nil, kCFStringTransformStripDiacritics, false)
print(mutableString) // prints: matreska