Programmatically add custom event in the iPhone Calendar

You can do this using the Event Kit framework in OS 4.0.

Right click on the FrameWorks group in the Groups and Files Navigator on the left of the window. Select 'Add' then 'Existing FrameWorks' then 'EventKit.Framework'.

Then you should be able to add events with code like this:

#import "EventTestViewController.h"
#import <EventKit/EventKit.h>

@implementation EventTestViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    EKEventStore *eventStore = [[EKEventStore alloc] init];

    EKEvent *event  = [EKEvent eventWithEventStore:eventStore];
    event.title     = @"EVENT TITLE";

    event.startDate = [[NSDate alloc] init];
    event.endDate   = [[NSDate alloc] initWithTimeInterval:600 sinceDate:event.startDate];

    [event setCalendar:[eventStore defaultCalendarForNewEvents]];
    NSError *err;
    [eventStore saveEvent:event span:EKSpanThisEvent error:&err];       
}

@end

Yes there still is no API for this (2.1). But it seemed like at WWDC a lot of people were already interested in the functionality (including myself) and the recommendation was to go to the below site and create a feature request for this. If there is enough of an interest, they might end up moving the ICal.framework to the public SDK.

https://developer.apple.com/bugreporter/

Based on Apple Documentation, this has changed a bit as of iOS 6.0.

1) You should request access to the user's calendar via "requestAccessToEntityType:completion:" and execute the event handling inside of a block.

2) You need to commit your event now or pass the "commit" param to your save/remove call

Everything else stays the same...

Add the EventKit framework and #import <EventKit/EventKit.h> to your code.

In my example, I have a NSString *savedEventId instance property.

To add an event:

    EKEventStore *store = [EKEventStore new];
    [store requestAccessToEntityType:EKEntityTypeEvent completion:^(BOOL granted, NSError *error) {
        if (!granted) { return; }
        EKEvent *event = [EKEvent eventWithEventStore:store];
        event.title = @"Event Title";
        event.startDate = [NSDate date]; //today
        event.endDate = [event.startDate dateByAddingTimeInterval:60*60];  //set 1 hour meeting
        event.calendar = [store defaultCalendarForNewEvents];
        NSError *err = nil;
        [store saveEvent:event span:EKSpanThisEvent commit:YES error:&err];
        self.savedEventId = event.eventIdentifier;  //save the event id if you want to access this later
    }];

Remove the event:

    EKEventStore* store = [EKEventStore new];
    [store requestAccessToEntityType:EKEntityTypeEvent completion:^(BOOL granted, NSError *error) {
        if (!granted) { return; }
        EKEvent* eventToRemove = [store eventWithIdentifier:self.savedEventId];
        if (eventToRemove) {
            NSError* error = nil;
            [store removeEvent:eventToRemove span:EKSpanThisEvent commit:YES error:&error];
        }
    }];

This adds events to your default calendar, if you have multiple calendars then you'll have find out which one that is

Swift version

You need to import the EventKit framework

import EventKit

Add event

let store = EKEventStore()
store.requestAccessToEntityType(.Event) {(granted, error) in
    if !granted { return }
    var event = EKEvent(eventStore: store)
    event.title = "Event Title"
    event.startDate = NSDate() //today
    event.endDate = event.startDate.dateByAddingTimeInterval(60*60) //1 hour long meeting
    event.calendar = store.defaultCalendarForNewEvents
    do {
        try store.saveEvent(event, span: .ThisEvent, commit: true)
        self.savedEventId = event.eventIdentifier //save event id to access this particular event later
    } catch {
        // Display error to user
    }
}

Remove event

let store = EKEventStore()
store.requestAccessToEntityType(EKEntityTypeEvent) {(granted, error) in
    if !granted { return }
    let eventToRemove = store.eventWithIdentifier(self.savedEventId)
    if eventToRemove != nil {
        do {
            try store.removeEvent(eventToRemove, span: .ThisEvent, commit: true)
        } catch {
            // Display error to user
        }
    }
}