利用字典NSMutableDictionary 转换为键/值格式的数据
初始化字典

NSMutableDictionary *cookieDict = [NSMutableDictionary dictionary];

获取当前页面的cookie，并将其转换为字典

NSArray *nCookies = [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookies];
NSHTTPCookie *cookie;
for (id c in nCookies){
    if ([c isKindOfClass:[NSHTTPCookie class]]){
        cookie=(NSHTTPCookie *)c;
        [cookieDict setObject:cookie.value forKey:cookie.name];
    }
}
NSLog(@"cookie...%@", cookieDict);

将字典转换为json串

//判断当前对象是否能够转换成JSON数据
BOOL isYes = [NSJSONSerialization isValidJSONObject:cookieDict];
if (isYes) {
    NSLog(@"可以转换");
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:cookieDict options:0 error:NULL];
    NSLog(@"%@", [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding]);
} else {
    NSLog(@"JSON数据生成失败，请检查数据格式");
}