Iphone EKEvent alarm AlertView在不到一秒钟内消失

已成功添加事件，并在事件开始时间前播放10秒（用于测试目的）的警报。问题是警报会触发（iPhone上的UIAlertView显示），但不到一秒钟就会消失。很奇怪

有什么问题吗

代码：

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请参阅下面的代码，希望对您有所帮助

 EKEventStore *eventStore = [[EKEventStore alloc] init];  
    EKEvent *event = [EKEvent eventWithEventStore:eventStore];
   event.title  = [NSString stringWithFormat:@"%@'s Birthday",strName];
   NSDate *twoYearsFromNow = [NSDate dateWithTimeIntervalSinceNow:1577846275];
    double alarmAmountInSeconds = 60*60*9;
   EKAlarm *alarm = [EKAlarm alarmWithRelativeOffset:(1.0*alarmAmountInSeconds)];
   EKRecurrenceRule *recurrance;
   recurrance = [[EKRecurrenceRule alloc] initRecurrenceWithFrequency:EKRecurrenceFrequencyYearly interval:1 end:[EKRecurrenceEnd recurrenceEndWithEndDate:twoYearsFromNow]];
   NSMutableArray *arrayReccurence = [NSMutableArray arrayWithObject:recurrance];
   event.recurrenceRules = arrayReccurence;
   event.startDate = startDate;
    event.endDate  = [[NSDate alloc] initWithTimeInterval:600 sinceDate:event.startDate];
   event.allDay = true;
    event.alarms = [NSArray arrayWithObject:alarm];

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

 EKEventStore *eventStore = [[EKEventStore alloc] init];  
    EKEvent *event = [EKEvent eventWithEventStore:eventStore];
   event.title  = [NSString stringWithFormat:@"%@'s Birthday",strName];
   NSDate *twoYearsFromNow = [NSDate dateWithTimeIntervalSinceNow:1577846275];
    double alarmAmountInSeconds = 60*60*9;
   EKAlarm *alarm = [EKAlarm alarmWithRelativeOffset:(1.0*alarmAmountInSeconds)];
   EKRecurrenceRule *recurrance;
   recurrance = [[EKRecurrenceRule alloc] initRecurrenceWithFrequency:EKRecurrenceFrequencyYearly interval:1 end:[EKRecurrenceEnd recurrenceEndWithEndDate:twoYearsFromNow]];
   NSMutableArray *arrayReccurence = [NSMutableArray arrayWithObject:recurrance];
   event.recurrenceRules = arrayReccurence;
   event.startDate = startDate;
    event.endDate  = [[NSDate alloc] initWithTimeInterval:600 sinceDate:event.startDate];
   event.allDay = true;
    event.alarms = [NSArray arrayWithObject:alarm];

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