检查日历上是否存在事件

Question

我无法验证用户日历上是否已存在某个事件.我需要检查这个以确定是否应该添加它,以便我不创建重复的日历条目.现在,我每次运行代码时都会创建一个重复的条目.

首先,这是我创建日历条目的方式:

+ (NSString *) addEventToCalenderWithDate : (NSDate *) eventDate
                               eventTitle : (NSString *) eventTitle
                            eventLocation : (NSString *) eventLocation
                              allDayEvent : (BOOL) isAllDay
{
    EKEventStore *store = [[EKEventStore alloc] init];

[store requestAccessToEntityType:EKEntityTypeEvent completion:^(BOOL granted, NSError *error) {

    if (!granted) {

        returnValue = @"calendar error";

    }

    else if ([self eventExists:dateAndTime eventTitle:eventTitle allDayEvent:isAllDay]) {

        returnValue = @"duplicate";

    }

    else {

        EKEvent *event = [EKEvent eventWithEventStore:store];
        event.title = eventTitle;

        event.startDate = dateAndTime;

        if (eventTimeString == (id)[NSNull null] || eventTimeString.length == 0 || isAllDay) {
            event.allDay = YES;
            event.endDate = dateAndTime;
        } else {
            event.endDate = [event.startDate dateByAddingTimeInterval:60*60];  //set 1 hour meeting
        }

        event.location = eventLocation;
        [event setCalendar:[store defaultCalendarForNewEvents]];
        NSError *err = nil;
        [store saveEvent:event span:EKSpanThisEvent commit:YES error:&err];

        returnValue = @"success";
    }
}];

return returnValue;


}

这会正确设置事件.但是,如果我再次运行它,我希望else if子句将返回,YES并且不会创建新条目.但是,它总是返回,NO并且每次执行时都会创建一个新的日历条目.这是方法:

+ (BOOL) eventExists : (NSDate *) date
          eventTitle : (NSString *) eventTitle
         allDayEvent : (BOOL) isAllDay
{
    EKEventStore *store = [[EKEventStore alloc] init];

    NSPredicate *predicateForEventOnDate = [[NSPredicate alloc] init];

    if (isAllDay)
        predicateForEventOnDate = [store predicateForEventsWithStartDate:date endDate:date calendars:nil]; // nil will search through all calendars
    else
        predicateForEventOnDate = [store predicateForEventsWithStartDate:date endDate:[date dateByAddingTimeInterval:60*60] calendars:nil]; // nil will search through all calendars

    NSArray *eventOnDate = [store eventsMatchingPredicate:predicateForEventOnDate];
    NSLog(@"eventOnDate: %@", eventOnDate);

    BOOL eventExists = NO;

    for (EKEvent *eventToCheck in eventOnDate) {
        if ([eventToCheck.title isEqualToString:eventTitle]) {
            eventExists = YES;
        }
    }

    return eventExists;
}

当我逐步完成这个方法时,我注意到被NSArray调用的eventOnDate是nil(EKEventStore不是nil).我不知道这是否意味着它根本没有找到任何匹配事件或者其他事情正在发生.

我做错了什么,不允许它识别日历上的现有事件？谢谢!

Answer 1

问题似乎与您为谓词选择的日期范围有关.

predicateForEventOnDate = [store predicateForEventsWithStartDate:date endDate:date calendars:nil];

这将查找"0"秒范围内的事件,因为谓词查询的开始和结束日期是相同的.

predicateForEventOnDate = [store predicateForEventsWithStartDate:date endDate:[date dateByAddingTimeInterval:60*60] calendars:nil];

这只会查找在提供日期的一小时内发生的事件.

NSCalendar *const calendar = NSCalendar.currentCalendar;
NSCalendarUnit const preservedComponents = (NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay);

//strip away hours, minutes and seconds to find date - at start of day
NSDateComponents *startComponents = [calendar components:preservedComponents fromDate:self.date];
//set finished date to 1 full day later
NSDateComponents *offset = [[NSDateComponents alloc] init];
[offset setDay:1];

NSDate *start = [calendar dateFromComponents:startComponents];
NSDate *finish = [calendar dateByAddingComponents:offset toDate:self.date options:0];

NSPredicate *predicateForEventOnDate = [[NSPredicate alloc] init];

if (isAllDay)
    predicateForEventOnDate = [store predicateForEventsWithStartDate:start endDate:finish calendars:nil];

NSArray *eventOnDate = [store eventsMatchingPredicate:predicateForEventOnDate];

这将生成一个数组,涵盖从头到尾一整天的事件.