ios - Length of String as extension of String -

i know there lots of pointers duplicates worked before updated xcode 6.3 , has problem it.

the script:

extension string {      func removecharsfromend(count:int) -> string {         var getself = self string         var stringlength = count(getself.utf16)          let substringindex = (stringlength < count) ? 0 : stringlength - count          return self.substringtoindex(advance(self.startindex, substringindex))     } } 

error : cannot invoke 'count' argument of list of type '(string.utf16view)'

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i want point out new method counting works everywhere else have used out (outside of extension).

thanks in advance.

count name of extension method parameter , hides swift library function count(). can rename parameter or call

var stringlength = swift.count(getself.utf16) 

explicitly.

but note counting number of utf-16 code units wrong here, should

var stringlength = swift.count(getself) 

to count number of characters in string, because advance() counts. can verify with

let foo = "😀😁😂".removecharsfromend(1) println(foo) 

here simplified version of method:

extension string {      func removecharsfromend(count : int) -> string {         precondition(count >= 0, "attempt call removecharsfromend() negative count")         // decrement `endindex` `count`, not beyond `startindex`:         let idx = advance(self.endindex, -count, self.startindex)         return self.substringtoindex(idx)     } } 

using three-argument version of advance() negative distance.

update swift 2/xcode 7:

extension string {      func removecharsfromend(count : int) -> string {         precondition(count >= 0, "attempt call removecharsfromend() negative count")         // decrement `endindex` `count`, not beyond `startindex`:         let idx = self.endindex.advancedby(-count, limit: self.startindex)         return self.substringtoindex(idx)     } }