Object 核心数据更新方法

我想为我的核心数据类实现更新方法，但有问题

-(BOOL)updateFromObject:(NSPredicate *)_find ToDesire:(NSPredicate *)_desire {

    NSFetchRequest *request = [[NSFetchRequest alloc]init];
    [request setEntity:entitydescription];
    [request setPredicate:_find];
    NSError *error = nil;
    NSArray *matchData = [context executeFetchRequest:request error:&error];
    if (matchData.count <=0) {
        NSLog(@"Nothing to do");
        return NO;
    }
    else {
        for (NSManagedObject *obj in matchData) {
            /*
            this is my problem
            how could i update my _desire to my object 
            */
        }
        [context save:&error];
        return YES;
    }
}

-（BOOL）updateFromObject:（NSPredicate*）\u查找到的目标：（NSPredicate*）\u需要{
NSFetchRequest*request=[[NSFetchRequest alloc]init]；
[请求集合实体：entitydescription]；
[请求集谓词：_find]；
n错误*错误=nil；
NSArray*matchData=[context executeFetchRequest:请求错误：&错误]；
如果（matchData.count最后我做了

-(BOOL)updateFromObject:(NSPredicate *)_find withNewData:(NSDictionary *)_data {
    NSFetchRequest *request = [[NSFetchRequest alloc]init];
    [request setEntity:entitydescription];
    [request setPredicate:_find];
    NSError *error = nil;
    NSArray *matchData = [context executeFetchRequest:request error:&error];
    if (matchData.count <=0) {
        NSLog(@"Nothing to update");
        return NO;
    }
    else {
        for (NSManagedObject *obj in matchData) {
            //obj = [[NSManagedObject alloc]];
            [obj setValuesForKeysWithDictionary:_data];
        }
        [context save:&error];
        return YES;
    }
}

-（BOOL）updateFromObject:（NSPredicate*）\u使用新数据查找：（NSDictionary*）\u数据{
NSFetchRequest*request=[[NSFetchRequest alloc]init]；
[请求集合实体：entitydescription]；
[请求集谓词：_find]；
n错误*错误=nil；
NSArray*matchData=[context executeFetchRequest:请求错误：&错误]；
if（matchData.count）谓词用于过滤一组对象。谓词不描述可以设置的值。如果调用此函数，
ToDesire
参数将是什么？