微信发票开发的iOS流程

1、使用GET请求获取微信access_token

access_token是公众号的全局唯一接口调用凭据，公众号调用各接口时都需使用access_token。开发者需要进行妥善保存。access_token的存储至少要保留512个字符空间。access_token的有效期目前为2个小时，需定时刷新，重复获取将导致上次获取的access_token失效。建议公众号开发者使用中控服务器统一获取和刷新access_token，其他业务逻辑服务器所使用的access_token均来自于该中控服务器，不应该各自去刷新，否则容易造成冲突，导致access_token覆盖而影响业务。关于 access_token 的更多介绍，请参考公众号开发文档。 请求方式
请求URL：https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=APPID&secret=APPSECRET
请求方法：GET

    NSDictionary *parm = @{
                           @"grant_type":@"client_credential",
                           @"appid":appid,
                           @"secret":secret,
                           };
    NSString *url = @"https://api.weixin.qq.com/cgi-bin/token";

2、使用拿到的access_token通过GET请求拿到ticket

ticket用于加强安全性。ticket的有效期目前为2个小时，需定时刷新。建议公众号开发者使用中控服务器统一获取和刷新ticket。 请求方式
请求URL：https://api.weixin.qq.com/cgi-bin/ticket/getticket?access_token=ACCESS_TOKEN&type=wx_card
请求方法：GET

    NSDictionary *parm = @{
                           @"type":@"wx_card",
                           @"access_token":token,
                           };
    NSString *url = @"https://api.weixin.qq.com/cgi-bin/ticket/getticket";

3、对拿到的ticket等信息进行排序加密,生成cardSign

卡券签名cardSign说明
1.将 api_ticket、appid、location_id、timestamp、nonce_str、card_id、card_type的value值进行字符串的字典序排序。
2.将所有参数字符串拼接成一个字符串进行sha1加密，得到cardSign。

    NSMutableDictionary *cardSignDic = [NSMutableDictionary dictionary];
    [cardSignDic setObject:nonceStr forKey:@"nonceStr"];
    [cardSignDic setObject:timeStr forKey:@"timestamp"];
    [cardSignDic setObject:apiTicket forKey:@"api_ticket"];
    [cardSignDic setObject:@"INVOICE" forKey:@"cardType"];
    [cardSignDic setObject:appid forKey:@"appid"];
    NSMutableString *contentString = [NSMutableString string];
    NSArray *values = [cardSignDic allValues];
    //按字母顺序排序
    NSArray *sortedArray = [values sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
        return [obj1 compare:obj2 options:NSNumericSearch];
    }];
    //拼接字符串
    for (NSString *value in sortedArray) {
        [contentString appendFormat:@"%@", value];
    }
    NSString *cardSign = [self sha1:contentString];

sha1加密：

- (NSString *)sha1:(NSString *)input {
    NSData *data = [input dataUsingEncoding:NSUTF8StringEncoding];
    uint8_t digest[CC_SHA1_DIGEST_LENGTH];
    CC_SHA1(data.bytes, (unsigned int)data.length, digest);
    NSMutableString *output = [NSMutableString stringWithCapacity:CC_SHA1_DIGEST_LENGTH * 2];
    for(int i = 0; i < CC_SHA1_DIGEST_LENGTH; i++){
        [output appendFormat:@"%02x", digest[i]];
    }
    return output;
}

4、通过调用微信Api跳转微信(注：传入的时间戳要和之前进行sha1加密的时间戳相同)

    WXChooseInvoiceReq *cardReq = [[WXChooseInvoiceReq alloc]init];
    cardReq.appID = appid;
    cardReq.timeStamp = timeStamp;
    cardReq.nonceStr = @"sfim_invoice";
    cardReq.cardSign = cardSign;
    [WXApi sendReq:cardReq];

5、在AppDelegate转发回调

- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation {
    if ([WXApi handleOpenURL:url delegate:[weChatManager shareInstance]]) {
        return YES;
    }
    if ([self application:application handleOpenURL:url]) {
        return YES;
    }
    return NO;
}

6、在onResp方法里拿到发票的id,再用POST请求 拿到发票详细的信息

 WXChooseInvoiceResp *chooseInvoiceResp = (WXChooseInvoiceResp *)resp;
 NSArray *itemArray = chooseInvoiceResp.cardAry;
 NSMutableArray *resultArray = [NSMutableArray arrayWithCapacity:itemArray.count];
 for (WXInvoiceItem *item in itemArray) {
        NSMutableDictionary *dicM = [NSMutableDictionary dictionary];
        [dicM setObject:item.cardId ? item.cardId : @"" forKey:@"card_id"];
        [dicM setObject:item.encryptCode ? item.encryptCode : @"" forKey:@"encrypt_code"];
        [resultArray addObject:dicM];
}
NSDictionary *listParm = @{
                           @"item_list":resultArray,
                           };
NSString *url = [NSString stringWithFormat:@"https://api.weixin.qq.com/card/invoice/reimburse/getinvoicebatch?access_token=%@",self.accessToken];

done