核心數據：更新對應於密鑰的數據

Question

如何更新對應於核心數據中的任何密鑰的數據？

感謝

Answer 1

用於更新核心數據中的任何條目，你需要先獲取該條目，然後讓對象爲實體然後設置的所有屬性看到這個代碼，

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");