How to remove diacritics from a String in Swift?

You can operate directly on a Swift String (if “Foundation” is imported):

let foo = "één"
let bar = foo.stringByFoldingWithOptions(.DiacriticInsensitiveSearch, locale: NSLocale.currentLocale())
print(bar) // een

Swift 3:

let foo = "één"
let bar = foo.folding(options: .diacriticInsensitive, locale: .current)
print(bar) // een