无法以字符串来查询，使用汉字查询，发现查询不出来

[wuyaomin]

User *user = [[User alloc] init];
user.name = @"zhangsan";
[user save];

NSString *ttString = [NSString stringWithFormat:@" WHERE name = %@ ",@"zhangsan"];
User *checkUser =[User findFirstByCriteria:ttString]；

[wuyaomin]

擦，我自己犯的错误，这个错误低端了 NSString *ttString = [NSString stringWithFormat:@" WHERE name = ‘%@’ ",@"zhangsan"];