在NSDefaults中使用NSDate作爲唯一標識符

Question

我遇到了一個問題，我將一個NSUserDefault鍵設置爲「currentDate」，但它的值似乎是4秒後，然後是存儲在CoreData中的值。我使用下面的代碼中看到的'currentDate'NSDate值。我認爲這是因爲當它保存NSUserDefaults時，它在4秒之後再次抓取日期選擇器當前日期？我將如何解決這個問題？

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

您沒有對您的託管對象和用戶默認密鑰使用相同的日期。您可以使用currentDate。

entry.date = currentDate;