Question

如何在关闭时让我的应用程序存储信息。因为每次重新打开它都会删除所有核心数据。

以下是一个例子：

NSString *nomville = [[_jsonDict objectAtIndex:indexPath.row] objectForKey:@"label"];
NSString *idVille = [[_jsonDict objectAtIndex:indexPath.row] objectForKey:@"id"];

detailView.title = nomville;
detailView.idVille = idVille;

NSLog(@"Valor: %@", nomville);
NSLog(@"Valor: %@", idVille);

AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];

NSManagedObjectContext *context = [appDelegate managedObjectContext];
NSManagedObject *villesR = [NSEntityDescription
                                   insertNewObjectForEntityForName:@"Ville"
                                   inManagedObjectContext:context];
[villesR setValue:idVille forKey:@"idV"];
[villesR setValue:nomville forKey:@"nom"];

[self.navigationController pushViewController:detailView animated:YES];

Answer 1

当您将应用推送到后台或退出时，通常会调用保存方法。

侯可以在你的app delegate中这样做：

- (void)applicationDidEnterBackground:(UIApplication *)application {
    [self saveContext];
}

- (void)applicationWillTerminate:(UIApplication *)application {
    [self saveContext];
}

#pragma mark - Core Data stack

- (void)saveContext {
    NSError *error = nil;
    NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
    if (managedObjectContext != nil) {
        if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
            abort();
        } 
    }
}

关闭应用程序时，将删除Core Data中保存的元素

1 个答案: