IOS: Graceful implementation of substring in Swift

In Swift, when we want to intercept a string, the method is as follows:

" Shanghai A12345 "  == Advance (StartIndex, 1= StartIndex: <//Output Shanghai

Well, I miss the substring method, so let's make it ourselves.

extension String {    subscript (r:range<Int>), string {        get {            = Advance ( Self.startindex, r.startindex)            = Advance (StartIndex, R.endindex- r.startindex)                        return  Self[range (Start:startindex, End:endindex)]     }}}

The invocation is simple, with the following examples:

" Hello, playground. " println (s[0 ... " Hello, " println (s[0 . " Hello "

Thanks to Rob Napier http://stackoverflow.com/questions/24044851/ How-do-you-use-string-substringwithrange-or-how-do-ranges-work-in-swift

IOS: Graceful implementation of substring in Swift