核心数据：更新与密钥对应的数据

Question

如何更新核心数据中任何键对应的数据？

由于

Answer 1

要更新核心数据中的任何条目，您需要先获取该条目，然后为该实体创建对象，然后设置其所有属性，请参阅此代码，

NSMutableArray *fetchResults;
    NSString *entityName=@"YourEntity";
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:entityName inManagedObjectContext:globalManagedObjectContext];
    [fetchRequest setEntity:entity];

    fetchResults = [NSMutableArray arrayWithArray:[globalManagedObjectContext executeFetchRequest:fetchRequest error:nil]];
    [fetchRequest release];

[fetchResults filterUsingPredicate:[NSPredicate predicateWithFormat:@"id==%@",comparing_key]];
    objEntity=[fetchResults objectAtIndex:0];

    objEntity.pro1=@"some value";
    objEntity.pro2=@"some value";

    if (![globalManagedObjectContext save:nil]) 
        NSLog(@"Error in storing to database");