The following document explains how to respond to an event invitation using the iOS 7 Calendar app (iPhone, iPad, or iPod Touch).
If you have been invited to a meeting and you have enabled "New Invitation Alerts" in the iPhone Settings, when you next open iPhone Calendar after the invite has been received on the iPhone, a pop-up alert will appear saying "Event Request Notification: " with the event details listed below.
The main icon for the iPhone Calendar located on the homepage will display a red circle with the number of invitations at the top right corner. In the iPhone Calendar application an Inbox button at the bottom-right of the iPhone Calendar display will be modified to indicate the number of invitations iPhone Calendar has received. If there are unviewed invitations, the number of unviewed invitations will show in parentheses after this Inbox button.
On the calendar display, events with invitations to which you have not responded to appear colored gray.
When you Accept a meeting invitation, the event stays in the calendar to which it belongs and iPhone Calendar displays it in the appropriate color. When you respond Maybe to an invitation, it is removed from the Invitations list. The color in iPhone Calendar's display changes to indicate its pending status to the color of the calendar with gray diagonal lines through it. See "Tap on a gray-colored event" below to see how to change your response status after you have selected Maybe as a response to an invitation. When you Decline a meeting invitation, the event disappears completely. iPhone Calendar provides no mechanism to retrieve or view declined events, even if "Show Declined Events" is turned on. Once they are declined they are 'gone' and cannot be seen again on the iPhone. Acting with appropriate caution is advised.
Note: you cannot Decline if using an iPad with iOS version 9.1 or above. You will have to Decline in a different client.
You can respond to invitations in several ways: