objective c - concatenate NSString with loop -

i have code below, creates loop , loop inserting values ​​into variable:

int i; nsstring *idts;  for(i=0;i<11;i++){  idts = [nsstring stringwithformat:@"%d<-+->",i];  }  nslog(@"order -> %@",idts); 

i wonder how concatenate values ​​of variable "idts" inside loop, because console shows me following message:

10<-+->

while, should appear follows:

1<-+->2<-+->3<-+->4<-+->5<-+->6<-+->7<-+->8<-+->9<-+->10

someone can me?

should this:

nsstring *idts = @"";  for(int i=0;i<11;i++){      idts = [nsstring stringwithformat:@"%@%d<-+->", idts, i];  } 

otherwise, not adding current string, you're overwriting variable.

update

based on @anon's comment, here's way exact output question:

nsstring *idts = @"";  for(int i=0;i<11;i++){      idts = [nsstring stringwithformat:@"%@%d%@", idts, i, (i != 10) ? @"<-+->" : @""];  } 

and @rmaddy's - mutable string more efficient

nsmutablestring *idts = [nsmutablestring string];  for(int i=0;i<11;i++){      [idts appendformat:@"%d%@", i, (i != 10) ? @"<-+->" : @""];  }