Question

我正在尝试使用以下代码将实体插入或更新（如果存在）一个实体：

- (void)insertFriendWithDictionary:(NSDictionary *)friendInfo {

    NSFetchRequest *req = [[NSFetchRequest alloc] initWithEntityName:@"Friend"];

    NSString *atributeName = @"identifier";
    NSString *valueName = [[friendInfo objectForKey:@"id"] stringFromMD5];

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"%K like %@",atributeName,valueName ];
    req.predicate = predicate;

    req.fetchLimit = 1;
    NSError *requestError = nil;
    NSArray *tmp = [self.managedObjectContext executeFetchRequest:req error:&requestError];

    if (tmp && tmp.count >0) {
        Friend *friend = [tmp objectAtIndex:0];
        friend.name = [friendInfo objectForKey:@"name"];
        friend.identifier = [NSString stringWithFormat:@"%@",[[friendInfo objectForKey:@"id"] stringFromMD5]];
        [self saveContext];
        return;
    }   

    Friend *friend = 
    [NSEntityDescription insertNewObjectForEntityForName:@"Friend"
                                  inManagedObjectContext:self.managedObjectContext];
    friend.name = [friendInfo objectForKey:@"name"];
    friend.identifier = [friendInfo objectForKey:@"id"];
    friend.noOfMessagesReceived = [NSNumber numberWithInt:0];
    friend.email = @"";
    friend.selected = [NSNumber numberWithBool:NO];
    friend.frooiFriend = [NSNumber numberWithBool:NO];
}

但是第二次运行代码时，谓词与任何结果都不匹配。我相信这是NSPredicate的一个问题。

以下是为朋友生成的代码：

@interface Friend : NSManagedObject

@property (nonatomic, retain) NSString * email;
@property (nonatomic, retain) NSNumber * frooiFriend;
@property (nonatomic, retain) NSString * identifier;
@property (nonatomic, retain) NSString * name;
@property (nonatomic, retain) NSNumber * noOfMessagesReceived;
@property (nonatomic, retain) NSData * profileImage;
@property (nonatomic, retain) NSNumber * selected;
@property (nonatomic, retain) NSNumber * frooliMessagesSentTo;

@end

我做错了吗？

由于

Answer 1

[friendInfo objectForKey:@"id"]是否等于[[friendInfo objectForKey:@"id"] stringFromMD5]？

如果不是：这是您的问题，因为您为新朋友设置了friend.identifier = [friendInfo objectForKey:@"id"];，但您搜索朋友的谓词使用了[[friendInfo objectForKey:@"id"] stringFromMD5]。

Answer 2

尝试使用此谓词：

[NSPredicate predicateWithFormat:@"%@ MATCHES[cd] '.*%@.*'",atributeName,valueName ];

这不是最好的表现，但它有效。之后你可以改善表现。

ios如何正确使用NSPredicate与Core Data匹配NSString？

2 个答案: