How would I go about removing the "&expires\_in=87131" within the following `NSString`:

Obviously the value 87131 may change in the future and it's always the last part of the string as well.

```
NSString *accessToken = @"136369349714439%7C2.nNIKZW8Z7Yw_aaaffqKv7lVFYJg__.86400.1301824800-705896566%7Cp-z9A68pJqTDNjEMj0TrHogc2bw&expires_in=87131";
NSString *newStr = [accessToken stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

```