[Solved] Swift 2.0 String behavior

Question

The index of a String is no more related to the number of characters (count) in Swift 2.0. It is an “opaque” struct (defined as CharacterView.Index) used only to iterate through the characters of a string. So even if it is printed as an integer, it should not be considered or used as an integer, to which, for instance, you can sum 2 to get the second character from the current one. What you can do is only to apply the two methods predecessor and successor to get the previous or successive index in the String. So, for instance, to get the second character from that with index idx in mixedString you can do:

mixedString[idx.successor().successor()]

Of course you can use more confortable ways of reading the characters of string, like for instance, the for statement or the global function indices(_:).

Consider that the main benefit of this approach is not to the threat multi-bytes characters in Unicode strings, as emoticons, but rather to treat in a uniform way identical (for us humans!) strings that can have multiple representations in Unicode, as different set of “scalars”, or characters. An example is café, that can be represented either with four Unicode “scalars” (unicode characters), or with five Unicode scalars. And note that this is a completely different thing from Unicode representations like UTF-8, UTF-16, etc., that are ways of mapping Unicode scalars into memory bytes.

Accepted Answer

The index of a String is no more related to the number of characters (count) in Swift 2.0. It is an “opaque” struct (defined as CharacterView.Index) used only to iterate through the characters of a string. So even if it is printed as an integer, it should not be considered or used as an integer, to which, for instance, you can sum 2 to get the second character from the current one. What you can do is only to apply the two methods predecessor and successor to get the previous or successive index in the String. So, for instance, to get the second character from that with index idx in mixedString you can do:

mixedString[idx.successor().successor()]

Of course you can use more confortable ways of reading the characters of string, like for instance, the for statement or the global function indices(_:).

Consider that the main benefit of this approach is not to the threat multi-bytes characters in Unicode strings, as emoticons, but rather to treat in a uniform way identical (for us humans!) strings that can have multiple representations in Unicode, as different set of “scalars”, or characters. An example is café, that can be represented either with four Unicode “scalars” (unicode characters), or with five Unicode scalars. And note that this is a completely different thing from Unicode representations like UTF-8, UTF-16, etc., that are ways of mapping Unicode scalars into memory bytes.