Problem in iOS 6.1 devices

[malihasulamanLoxvo]

application crashing

[__NSCFString boundingRectWithSize:options:attributes:context:]: unrecognized selector sent to instance 0x8b9fa20
2014-03-06 12:43:52.150 YodizChat[1729:907] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFString boundingRectWithSize:options:attributes:context:]: unrecognized selector sent to instance 0x8b9fa20'

[MohanAprdc]

Actually this is ios 7 compatible. Anyway I will check it for iOS 6 also.
Thank you for the comment.