If you use an over-the-air calendar on your iPhone, like iCloud or Microsoft Exchange, or use Mail on a Mac, you can invite people to your event directly from Calendar. Make sure you accurately complete the details of your event before sending it to the invitees. Then follow these steps:
Tap Invitees.
The Add Invitees screen opens.
Type in the e-mail addresses of the people you want to invite or tap the plus sign on the right.
Contacts opens. Scroll the list or tap the letters down the right side or use the Search function to find the name you're looking for.
Tap the name of the person you want to invite.
You return to the Add Invitees screen and the name appears in the space at the top.
Repeat Steps 2 and 3 to add more people.
Tap Add Event (or Edit if you are inviting people after an event has been created) in the upper right corner.
Tap Done.
An event invitation is automatically sent to your invitees.
Of course one of the easiest ways to add an event is to call on Siri. Press and hold the Home button until Siri appears and then speak the details of your event, such as “Set up a meeting with Joe on Thursday at 3 p.m.” or “Create a repeating event every Tuesday from 10:15 to noon.”
Siri asks the necessary questions to send invitations, add locations, and even edit events at a later date.