Programmatically add custom event in the iPhone Calendar

Is there any way to add iCal event to the iPhone Calendar from the custom App?

Leap year check using bitwise operators (amazing speed)

Someone on JSPerf dropped an amazingly fast implementation for checking leap years of the ISO calendar (link: Odd bit manipulations ):

How can I programmatically create an iCal event in the default calendar?

How can I use Objective-C to programmatically create an iCal event in the default calendar? I want to check whether the event already exists and set the button state accordingly.

Calendar synch?

I am looking to synchronize a google calendar into my in app calendar but I don't have any idea of how to do this. The idea is that the synchronized calendar could be seen by any user that has this app.

How can i get all calendar and its events from iphone app?

Good Day to you. I have used iCal events in my app. I have add events to iCal and retrieve/delete the events from iCal from my sample iPhone app. Now, i want to show all the calendars what are the calendars user synced in their iPhone(Eg : Google calendar). Then i want to retrieve the events from other calendars except iCal. How can i get all the synced calendars from iPhone? I searched my level best in Google but, can't to get right answer. Can you please help me? Thanks in advance.