oc 字典与字符串转换

1. 字典转字符串

// dic 为初始字典
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dic options:NSJSONWritingPrettyPrinted error:nil];
// json 为 转换后的 字符串
NSString *json = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];

2. 字符串转字典

- (NSDictionary *)dictionaryWithJsonString:(NSString *)jsonString {
    if (jsonString == nil) {
     return nil;
    }

    NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
    NSError *err;
    NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:jsonData
                                                       options:NSJSONReadingMutableContainers
                                                          error:&err];
    if(err) {
        NSString *log = [NSString stringWithFormat:@"%d, %s | json解析失败：%@", __LINE__, __func__, err];
        return nil;
    }
    return dic;
}

// jsonStr 是初始字符串， dic 为转换后的字典
NSDictionary *dic = [self dictionaryWithJsonString:jsonStr];