I have tried many times to convert the string 2013-01-27T02:31:47+08:00 into NSDate. I have found the formatting guide by apple and copied its code and tried ,
2013-01-27T02:31:47+08:00
Your format should be @"yyyy-MM-dd'T'HH:mm:ssZZZZZ". You only need single quotes around letters that are not going to be used by the formatter.
@"yyyy-MM-dd'T'HH:mm:ssZZZZZ"