核心数据：更新对应于密钥的数据

Question

如何更新对应于核心数据中的任何密钥的数据？

感谢

Answer 1

用于更新核心数据中的任何条目，你需要先获取该条目，然后让对象为实体然后设置的所有属性看到这个代码，

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");