在 NSDefaults 中使用 NSDate 作为唯一标识符

Question

我遇到了一个问题，我将 NSUserDefault 键设置为我的“currentDate”，但它的值似乎比存储在 CoreData 中的值晚 4 秒。我正在使用与下面代码中相同的“currentDate”NSDate 值。我认为这是因为它在保存 NSUserDefaults 后 4 秒又重新获取了日期选择器的当前日期？我该如何解决这个问题？

CoreDataStack *coreDataStack = [CoreDataStack defaultStack];
EventEntry *entry = [NSEntityDescription insertNewObjectForEntityForName:@"EventEntry" inManagedObjectContext:coreDataStack.managedObjectContext];
entry.title = self.titleField.text;
entry.date = self.datePicker.date.timeIntervalSinceNow;
[coreDataStack saveContext];
//Create the dateformatter object
NSDateFormatter* formatter = [[NSDateFormatter alloc] init];

//Set the required date format
[formatter setDateFormat:@"yyyy-MM-dd HH:mm a"];

NSCalendar *calender = [NSCalendar autoupdatingCurrentCalendar];
NSDate *currentDate = self.datePicker.date;
NSLog(@"Todays date is %@",[formatter stringFromDate:currentDate]);

NSDateComponents *dateComp = [NSDateComponents new];
notificationTime = -notificationTime;
[dateComp setMinute:notificationTime];
[dateComp setSecond:0];
NSDate *targetDate = [calender dateByAddingComponents:dateComp toDate:currentDate options:0];
NSLog(@"Local Notification is set for %@",[formatter stringFromDate:targetDate]);
UILocalNotification *localNotification = [[UILocalNotification alloc] init];
localNotification.fireDate = targetDate;
localNotification.alertBody = @"Testing Local Notification";
localNotification.soundName = UILocalNotificationDefaultSoundName;
[[UIApplication sharedApplication] scheduleLocalNotification:localNotification];


formatter.dateFormat = @"yyyy-MM-dd HH:mm:ss";
NSString *dateString = [formatter stringFromDate:currentDate];
NSLog(@"Date String Key: %@", dateString);
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:localNotification];
[userDefaults setObject:data forKey:dateString];
[userDefaults synchronize];

Answer 1

您的托管对象和用户默认密钥没有使用相同的日期。

您应该使用currentDate。

entry.date = currentDate;