iphone - 使用 NSJSONSerialization 将 NSMutableDictionary 转换为 JSON 返回不同的结果

Question

当我尝试使用 NSJSONSerialization 将 NSMutableDictionary 转换为 JSON 时，它返回不同的结果:

代码:

-(NSString*)JSONRepresentation{

    return [self JSONRepresentation:NO];
}

-(NSString*)JSONRepresentation:(BOOL)whiteSpaces{

    NSError* error = nil;
    NSData * result = nil;

    if(whiteSpaces)
        result = [NSJSONSerialization dataWithJSONObject:self options:NSJSONWritingPrettyPrinted error:&error];
    else
        result = [NSJSONSerialization dataWithJSONObject:self options:kNilOptions error:&error];

    if (error != nil){
        NSLog(@"Error:%@",error);
        return nil;
    }

    return [NSString stringWithUTF8String:[result bytes]];
}

这就是我的使用方式:

NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
[dict setObject:@"xxx" forKey:@"experiment"];

NSLog(@"(%@)", [dict JSONRepresentation]);

连续尝试的结果:

2013-08-01 12:31:45.066 Hercules Demo[8763:c07] ((null))
2013-08-01 12:31:49.988 Hercules Demo[8763:c07] ((null))
2013-08-01 12:31:52.838 Hercules Demo[8763:c07] ({"experiment":"xxx"})
2013-08-01 12:31:59.432 Hercules Demo[8763:c07] ({"experiment":"xxx"})
2013-08-01 12:32:03.160 Hercules Demo[8763:c07] ((null))
2013-08-01 12:32:06.232 Hercules Demo[8763:c07] ({"experiment":"xxx"})
2013-08-01 12:32:08.395 Hercules Demo[8763:c07] ((null))

Answer 1

dataWithJSONObject方法返回 NSData ，所以我建议:

1. 转换 NSData进入NSString ，你应该使用initWithData而不是stringWithUTF8String 。所以，而不是:

   return [NSString stringWithUTF8String:[result bytes]];
   

   你应该这样做:

   return [[NSString alloc] initWithData:result encoding:NSUTF8StringEncoding];
   

2. 为了清楚起见，您可能应该定义 result成为NSData *而不是id .