UILocalNotification未按正确时间触发

Question

我正在尝试设置UILocalNotification，但它没有按时开火。它会在2小时后发射然后应该发射。这是我如何计算提醒日期：

NSDate *etkinlikDate = [gregorian dateFromComponents: components];
sourceTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
destinationTimeZone = [NSTimeZone systemTimeZone];

sourceGMTOffset = [sourceTimeZone secondsFromGMTForDate:etkinlikDate];
destinationGMTOffset = [destinationTimeZone secondsFromGMTForDate:etkinlikDate];
interval = destinationGMTOffset - sourceGMTOffset;

etkinlikDate = [[NSDate alloc] initWithTimeInterval:interval sinceDate:etkinlikDate];

此处etkinlikDate会返回正确的值。 （我想发布通知的日期）

以及我如何设置警报：

UILocalNotification* localNotification = [[UILocalNotification alloc] init];
localNotification.soundName = UILocalNotificationDefaultSoundName;
localNotification.fireDate = etkinlikDate;
localNotification.alertBody = [NSString stringWithFormat: @"%@ %@", [sClass className], etkinlikSaati];
localNotification.soundName = @"receivedmessage.caf";
localNotification.alertAction = @"Show me the item %d";
localNotification.timeZone = [NSTimeZone systemTimeZone];
[[UIApplication sharedApplication] scheduleLocalNotification:localNotification];

// Request to reload table view data
[[NSNotificationCenter defaultCenter] postNotificationName:@"reloadData" object:self];

虽然正确设置了etkinlikDate，但本地通知未按时触发。

更新：让我们说我想在16:30设置警报。

etkinlikDate返回16:30，但在18:30发出警报。