iOS JSON NSString Convert to NSDictionary

NSString *str = @"{\"info\":{\"body\":\"这个里面是是测试代码,里面有二个图片<!--img#0--><br/><!--img#1-->\",\"img\":[{\"ref\":\"<!--img#0-->\",\"src\":\"http://img.baidu.com/img/iknow/wenku/huazhang315x150.jpg\"},{\"ref\":\"<!--img#1-->\",\"src\":\"http://img.baidu.com/img/iknow/wenku/lxg315X150-lxg.jpg\"}]}}";

NSError *error = nil;
NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary *jsonObject = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:&error];