core-data - 如何预填充数据库并在核心数据中设置标志以保证每次安装应用程序时我只将对象插入数据库一次

Question

我需要使用核心数据预填充我的数据库，但需要设置一个标志来指示应用程序是否在安装后首次启动。我不知道该怎么做？

这是我在 appDelegate.m 文件中所做的

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{


NSManagedObjectContext *context = [self managedObjectContext];



DJ *djsInfo = [NSEntityDescription
 insertNewObjectForEntityForName:@"DJ"
 inManagedObjectContext:context];

    /*DJ *djsInfo = [NSEntityDescription
                                  insertNewObjectForEntityForName:@"DJ"
                                  inManagedObjectContext:context];*/



djsInfo.name = @"DJ Smoke";
djsInfo.city = @"Chicago";
djsInfo.state = @"Illinois";
DJDetails *failedBankDetails = [NSEntityDescription
                                        insertNewObjectForEntityForName:@"DJDetails"
                                        inManagedObjectContext:context];
//failedBankDetails.closeDate = [NSDate date];
//failedBankDetails.updateDate = [NSDate date];
failedBankDetails.zip = [NSNumber numberWithInt:12345];
failedBankDetails.info = djsInfo;
djsInfo.details = failedBankDetails;


NSError *error;
if (![context save:&error]) {
    NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
}

Answer 1

尝试使用标准的用户默认机制。

if (![[NSUserDefaults standardUserDefaults] 
                         objectForKey:@"ThisAppWasLaunchedBefore"]) {
   [[NSUserDefaults standardUserDefaults] setBool:YES 
                                           forKey:@"ThisAppWasLaunchedBefore"];
  // do one-time setup stuff
 }