在iOS中添加新事件之前检查重复项目 - EKEventStore

Question

我是iOS编程的新手,我正在开发一个简单的项目,列出给定城市的假期,并让用户能够将这些事件添加到iCal默认日历中.

问题是:如何检查用户日历中是否已存在具有相同属性(例如标题和开始日期)的事件.如果多次按下操作按钮(用于向iCal添加事件),则可能发生这种情况.在这种情况下,我不希望在iCal中创建两个或更多相同的事件.

我曾试图使用NSPredicate,但我完全迷失了如何对它进行排序.

任何帮助都会受到赞赏!提前致谢.

贝娄是我的事件添加代码,只是为了让事情变得清晰.在这种情况下,用户正在从列表中添加多个事件(例如,所有本地假日).

for (int i = 0; i<[allHolidayNames count]; ++i) {

    // ------ EVENT MANIPULATION ------

    EKEventStore *eventStore = [[EKEventStore alloc] init];
    EKEvent *addEvent = [EKEvent eventWithEventStore:eventStore];
    addEvent.title = [allHolidayNames objectAtIndex:i];
    addEvent.startDate = [allHolidayDates objectAtIndex:i];
    addEvent.allDay = YES;
    [addEvent setCalendar:[eventStore defaultCalendarForNewEvents]];
    [eventStore saveEvent:addEvent span:EKSpanThisEvent commit:YES error:nil];
}   

Answer 1

摘要

在实例方法的某个时刻(可能在for循环期间),您将需要创建一个NSPredicate,[allHolidayDates objectAtIndex:i]以返回一个循环的数组,以检查[allHolidayNames objectAtIndex:i]返回的事件中是否存在.

示例代码

for (int i = 0; i<[allHolidayNames count]; ++i) {

    // ------ EVENT MANIPULATION ------

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

    NSPredicate *predicateForEventsOnHolidayDate = [eventStore predicateForEventsWithStartDate:[allHolidayDates objectAtIndex:i] endDate:[allHolidayDates objectAtIndex:i] calendars:nil]; // nil will search through all calendars

    NSArray *eventsOnHolidayDate = [eventStore eventsMatchingPredicate:predicateForEventsOnHolidayDate]

    BOOL eventExists = NO;

    for (EKEvent *eventToCheck in eventsOnHolidayDate) {
        if ([eventToCheck.title isEqualToString:[allHolidayNames objectAtIndex:i]]) {
            eventExists = YES;
        }
    }

    if (eventExists == NO) {
        EKEvent *addEvent = [EKEvent eventWithEventStore:eventStore];
        addEvent.title = [allHolidayNames objectAtIndex:i];
        addEvent.startDate = [allHolidayDates objectAtIndex:i];
        addEvent.allDay = YES;
        [addEvent setCalendar:[eventStore defaultCalendarForNewEvents]];
        [eventStore saveEvent:addEvent span:EKSpanThisEvent commit:YES error:nil];
    }
}

提示

• 为了帮助可视化数据,尤其是数组和对象的内容,请尝试使用NSLog.这会将对象的内容输出到控制台,以帮助您更好地理解数据结构.

  NSLog("eventsOnHolidayDate =%@",eventsOnHolidayDate);

• 请注意,eventsMatchingPredicate将在检索事件时阻止主线程.如果您连续多次这样做,可能会影响用户体验.你应该考虑使用enumerateEventsMatchingPredicate:usingBlock:(在这个问题的范围之外).