iOS10，首先需要满足相关权限：

日历权限

提醒权限

类型:

typedef NS_ENUM(NSUInteger, EKEntityType) {
    EKEntityTypeEvent//事件
    EKEntityTypeReminder//提醒
};

具体代码：

{
    //事件市场
    EKEventStore *eventStore = [[EKEventStore alloc] init];
    
    [eventStore requestAccessToEntityType:EKEntityTypeEvent completion:^(BOOL granted, NSError *error) {
        dispatch_async(dispatch_get_main_queue(), ^{
            if (error)
            {
                //错误信息
            }
            else if (!granted)
            {
                //被用户拒绝，不允许访问日历
            }
            else
            {
                //事件保存到日历
                
                //创建事件
                EKEvent *event  = [EKEvent eventWithEventStore:eventStore];
                event.title     = @"哈哈哈，我是提醒事件！";
                event.location = @"北三环东路甲5号";
                
                NSDateFormatter *tempFormatter = [[NSDateFormatter alloc] init];
                [tempFormatter setDateFormat:@"dd.MM.yyyy HH:mm"];
                
                event.startDate = [[NSDate alloc]init ];
                event.endDate   = [[NSDate alloc]init ];
                event.allDay = YES;
                event.notes = @"备注www.baidu.com";
                event.URL = [NSURL URLWithString:@"www.baidu.com"];
                //添加提醒
                [event addAlarm:[EKAlarm alarmWithRelativeOffset:60.0f * -60.0f * 24]];
                [event addAlarm:[EKAlarm alarmWithRelativeOffset:60.0f * -15.0f]];
                [event addAlarm:[EKAlarm alarmWithRelativeOffset:60.0f * -5.0f]];
                [event setCalendar:[eventStore defaultCalendarForNewEvents]];
                NSError *err;
                [eventStore saveEvent:event span:EKSpanThisEvent error:&err];
                
                UIAlertView *alert = [[UIAlertView alloc]
                                      initWithTitle:@"事件"
                                      message:@"添加成功"
                                      delegate:nil
                                      cancelButtonTitle:@"好的"
                                      otherButtonTitles:nil];
                [alert show];
                
                NSLog(@"保存成功");
                
            }
        });
    }];
  }