Many iPhone users have complained in Apple forums about a glitch in the new iOS in which their iMessages appear as sent, but later show up as unsent.
Possible solutions to the problem include restarting the device and resetting the original network settings. However, neither of the fixes has proved to be a long term solution for the issue.
“We are aware of an issue that affects a fraction of a percent of our iMessage users, and we will have a fix available in an upcoming software update,” Apple said in a statement. “In the meantime, we encourage any users having problems to reference our troubleshooting documents or contact AppleCare to help resolve their issue. We apologize for any inconvenience this causes impacted users.”
Apple's iOS7 was launched on September 18. So far, it has received similar amounts of praise and criticism for its new look and features.