I want to implement an iOS application which will use the SMS text as raw information. I think Apple does not allow this. Could an iOS application read/access SMS text? or do we have any other approach to do the same?
Modification: Can we read service messages which are not saved in the SMS box like balance message?
Correct, you cannot access these on a standard, non-jailbroken iPhone. You should file a bug with Apple, perhaps they'll improve SMS access in the future.
Check this
For SMS sending through application allowed but for accessing inbox for sms/email not allowed.
It is only possible when the phone is Jailbreaked. There are many tools to jailbreak your phone.
Once Jailbreaked, an application cal open the SQLite database at
/var/mobile/Library/SMS/sms.db and read the message table.
It contains, the date/time at which the message was received, the sender/recipient phone number and even the clear text of the message.