微信支付流程其实挺简单的，但苦逼的我需要在客户端下单，疯狂百度之后终于是搞定了，所以有必要把代码记录一下。
一，导入SDK
如果使用了分享的SDK中包含微信SDK，就不用再次导入了。

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依赖库

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二，配置
1.URL Types

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2.白名单

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三、代码导入
1.AppDelegate.m中

#import "WXApi.h"

<WXApiDelegate>

- (BOOL)application:(UIApplication *)app openURL:(NSURL *)url options:(NSDictionary<NSString *,id> *)options
{

    return [WXApi handleOpenURL:url delegate:self];
}
- (void)onResp:(BaseResp *)resp
{
    //支付返回结果，实际支付结果需要去微信服务器端查询
    NSString *strMsg = [NSString stringWithFormat:@"支付结果"];

    switch (resp.errCode) {
        case WXSuccess:
            strMsg = @"支付结果：成功！";
            NSLog(@"支付成功－PaySuccess，retcode = %d", resp.errCode);

            break;
        default:
            strMsg = [NSString stringWithFormat:@"支付结果：失败！retcode = %d, retstr = %@", resp.errCode,resp.errStr];
            NSLog(@"错误，retcode = %d, retstr = %@", resp.errCode,resp.errStr);

            break;
    }
    self.alipayNav = nil;
}

官方把代理写在了WXApiManager.h类里

2.支付文件中

//微信支付商户号
#define MCH_ID  @"10位数字那个"
//开户邮件中的（公众账号APPID或者应用APPID）
#define WX_AppID @"wx开头的那个"
//安全校验码（MD5）密钥，商户平台登录账户和密码登录http://pay.weixin.qq.com 平台设置的“API密钥”，为了安全，请设置为以数字和字母组成的32字符串。
#define WX_PartnerKey @"纯英文的那个"
//获取用户openid，可使用APPID对应的公众平台登录http://mp.weixin.qq.com 的开发者中心获取AppSecret。
#define WX_AppSecret @"app secret"

下单，个别参数在下面给出方法，我自己分装在其他类里了

//统一下单
- (void)order:(NSString *)tradeNo withMoney:(NSString *)price
｛
   NSString *appid = WX_AppID;
   NSString *mch_id = MCH_ID;
   NSString *partner = WX_PartnerKey;
   NSString *nonce_str =[self generateTradeNO];
   NSString *body = @"商品购买";
   NSString *out_trade_no = tradeNo;
   NSString *total_fee = [NSString stringWithFormat:@"%d",(int)([price floatValue]*10000/100)];
   NSString *notify_url = @"回调地址";
   NSString *spbill_create_ip = [getIPhoneIP getIPAddress:NO];
   NSString *trade_type = @"APP";
   
   DataMD5 *data = [[DataMD5 alloc] initWithAppid:appid mch_id:mch_id nonce_str:nonce_str partner_id:partner body:body out_trade_no:out_trade_no total_fee:total_fee spbill_create_ip:spbill_create_ip notify_url:notify_url trade_type:trade_type];
   NSString *sign = [data getSignForMD5];
   
   NSMutableDictionary *dic = [NSMutableDictionary dictionary];
   [dic setValue:appid forKey:@"appid"];//公众账号ID
   [dic setValue:mch_id forKey:@"mch_id"];//商户号
   [dic setValue:nonce_str forKey:@"nonce_str"];//随机字符串
   [dic setValue:sign forKey:@"sign"];//签名
   [dic setValue:body forKey:@"body"];//商品描述
   [dic setValue:out_trade_no forKey:@"out_trade_no"];//订单号
   [dic setValue:total_fee forKey:@"total_fee"];//金额,注意100=1元
   [dic setValue:spbill_create_ip forKey:@"spbill_create_ip"];//终端IP
   [dic setValue:notify_url forKey:@"notify_url"];//通知地址
   [dic setValue:trade_type forKey:@"trade_type"];//交易类型
   
   NSLog(@"+++%@",dic);
   
   NSString *xmlString = [dic XMLString];
   
   
   AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
   //这里传入的xml字符串只是形似xml，但是不是正确是xml格式，需要使用af方法进行转义
   manager.responseSerializer = [[AFHTTPResponseSerializer alloc] init];
   [manager.requestSerializer setValue:@"text/xml;charset=utf-8" forHTTPHeaderField:@"Content-Type"];
   [manager.requestSerializer setValue:@"https://api.mch.weixin.qq.com/pay/unifiedorder" forHTTPHeaderField:@"SOAPAction"];
   [manager.requestSerializer setQueryStringSerializationWithBlock:^NSString *(NSURLRequest *request, NSDictionary *parameters, NSError *__autoreleasing *error) {
       return xmlString;
   }];
   //发起请求
   [manager POST:@"https://api.mch.weixin.qq.com/pay/unifiedorder"
             parameters:xmlString
               progress:nil
                success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
                    NSString *responseString = [[NSString alloc] initWithData:responseObject encoding:NSUTF8StringEncoding] ;
                    // LXLog(@"responseString is %@",responseString);
                    //将微信返回的xml数据解析转义成字典
                    NSDictionary *dic = [NSDictionary dictionaryWithXMLString:responseString];
                    NSLog(@"++++++++++%@,%@",dic,[dic objectForKey:@"return_msg"]);
                    //此处为调起支付接口
                    [self WXPayRequest:appid nonceStr:[dic objectForKey:@"nonce_str"] package:@"Sign=WXPay" partnerId:[dic objectForKey:@"mch_id"] prepayId:[dic objectForKey:@"prepay_id"] timeStamp:@"1" sign:[dic objectForKey:@"sign"]];
                }
                failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
                    
                }];

}

支付：

//调起微信接口
- (void)WXPayRequest:(NSString *)appId nonceStr:(NSString *)nonceStr package:(NSString *)package partnerId:(NSString *)partnerId prepayId:(NSString *)prepayId timeStamp:(NSString *)timeStamp sign:(NSString *)sign{
    
    //调起微信支付
    
    PayReq* wxreq = [[PayReq alloc] init];
    wxreq.partnerId= partnerId;
    wxreq.prepayId= prepayId;
    wxreq.nonceStr= nonceStr;
    
    NSDate *date = [NSDate date];
    NSString *time1970 = [NSString stringWithFormat:@"%ld", (long)[date timeIntervalSince1970]];
    wxreq.timeStamp= [time1970 intValue];
    
    wxreq.package= package;
    DataMD5 *md5 = [[DataMD5 alloc] init];
    wxreq.sign=[md5 createMD5SingForPay:appId partnerid:wxreq.partnerId prepayid:wxreq.prepayId package:wxreq.package noncestr:wxreq.nonceStr timestamp:wxreq.timeStamp];
    [WXApi sendReq:wxreq];
}

3.nonce_str随机字符串的获得

- (NSString *)generateTradeNO {
    static int kNumber = 15;
    NSString *sourceStr = @"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    NSMutableString *resultStr = [[NSMutableString alloc] init];
    srand(time(0)); // 此行代码有警告:
    for (int i = 0; i < kNumber; i++) {
        unsigned index = rand() % [sourceStr length];
        NSString *oneStr = [sourceStr substringWithRange:NSMakeRange(index, 1)];
        [resultStr appendString:oneStr];
    }
    return resultStr;
}

4,IP地址的获得

#pragma mark - 获取设备当前网络IP地址
+ (NSString *)getIPAddress:(BOOL)preferIPv4
{
    NSArray *searchArray = preferIPv4 ?
    @[ IOS_VPN @"/" IP_ADDR_IPv4, IOS_VPN @"/" IP_ADDR_IPv6, IOS_WIFI @"/" IP_ADDR_IPv4, IOS_WIFI @"/" IP_ADDR_IPv6, IOS_CELLULAR @"/" IP_ADDR_IPv4, IOS_CELLULAR @"/" IP_ADDR_IPv6 ] :
    @[ IOS_VPN @"/" IP_ADDR_IPv6, IOS_VPN @"/" IP_ADDR_IPv4, IOS_WIFI @"/" IP_ADDR_IPv6, IOS_WIFI @"/" IP_ADDR_IPv4, IOS_CELLULAR @"/" IP_ADDR_IPv6, IOS_CELLULAR @"/" IP_ADDR_IPv4 ] ;
    
    NSDictionary *addresses = [self getIPAddresses];
    NSLog(@"addresses: %@", addresses);
    
    __block NSString *address;
    [searchArray enumerateObjectsUsingBlock:^(NSString *key, NSUInteger idx, BOOL *stop)
     {
         address = addresses[key];
         //筛选出IP地址格式
         if([self isValidatIP:address]) *stop = YES;
     } ];
    return address ? address : @"0.0.0.0";
}

+ (BOOL)isValidatIP:(NSString *)ipAddress {
    if (ipAddress.length == 0) {
        return NO;
    }
    NSString *urlRegEx = @"^([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\."
    "([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\."
    "([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\."
    "([01]?\\d\\d?|2[0-4]\\d|25[0-5])$";
    
    NSError *error;
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:urlRegEx options:0 error:&error];
    
    if (regex != nil) {
        NSTextCheckingResult *firstMatch=[regex firstMatchInString:ipAddress options:0 range:NSMakeRange(0, [ipAddress length])];
        
        if (firstMatch) {
            NSRange resultRange = [firstMatch rangeAtIndex:0];
            NSString *result=[ipAddress substringWithRange:resultRange];
            //输出结果
            NSLog(@"%@",result);
            return YES;
        }
    }
    return NO;
}

+ (NSDictionary *)getIPAddresses
{
    NSMutableDictionary *addresses = [NSMutableDictionary dictionaryWithCapacity:8];
    
    // retrieve the current interfaces - returns 0 on success
    struct ifaddrs *interfaces;
    if(!getifaddrs(&interfaces)) {
        // Loop through linked list of interfaces
        struct ifaddrs *interface;
        for(interface=interfaces; interface; interface=interface->ifa_next) {
            if(!(interface->ifa_flags & IFF_UP) /* || (interface->ifa_flags & IFF_LOOPBACK) */ ) {
                continue; // deeply nested code harder to read
            }
            const struct sockaddr_in *addr = (const struct sockaddr_in*)interface->ifa_addr;
            char addrBuf[ MAX(INET_ADDRSTRLEN, INET6_ADDRSTRLEN) ];
            if(addr && (addr->sin_family==AF_INET || addr->sin_family==AF_INET6)) {
                NSString *name = [NSString stringWithUTF8String:interface->ifa_name];
                NSString *type;
                if(addr->sin_family == AF_INET) {
                    if(inet_ntop(AF_INET, &addr->sin_addr, addrBuf, INET_ADDRSTRLEN)) {
                        type = IP_ADDR_IPv4;
                    }
                } else {
                    const struct sockaddr_in6 *addr6 = (const struct sockaddr_in6*)interface->ifa_addr;
                    if(inet_ntop(AF_INET6, &addr6->sin6_addr, addrBuf, INET6_ADDRSTRLEN)) {
                        type = IP_ADDR_IPv6;
                    }
                }
                if(type) {
                    NSString *key = [NSString stringWithFormat:@"%@/%@", name, type];
                    addresses[key] = [NSString stringWithUTF8String:addrBuf];
                }
            }
        }
        // Free memory
        freeifaddrs(interfaces);
    }
    return [addresses count] ? addresses : nil;
}

5.获取sign签名

///获取sign签名
- (NSString *)getSignForMD5{
    NSMutableDictionary *dic = [NSMutableDictionary dictionary];
    [dic setValue:_appid forKey:@"appid"];
    [dic setValue:_mch_id forKey:@"mch_id"];
    [dic setValue:_nonce_str forKey:@"nonce_str"];
    [dic setValue:_body forKey:@"body"];
    [dic setValue:_out_trade_no forKey:@"out_trade_no"];
    [dic setValue:_total_fee forKey:@"total_fee"];
    [dic setValue:_spbill_create_ip forKey:@"spbill_create_ip"];
    [dic setValue:_notify_url forKey:@"notify_url"];
    [dic setValue:_trade_type forKey:@"trade_type"];
    return [self createMd5Sign:dic];
}

//创建签名
-(NSString*) createMd5Sign:(NSMutableDictionary*)dict
{
    NSMutableString *contentString  =[NSMutableString string];
    NSArray *keys = [dict allKeys];
    //按字母顺序排序
    NSArray *sortedArray = [keys sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
        return [obj1 compare:obj2 options:NSNumericSearch];
    }];
    //拼接字符串
    for (NSString *categoryId in sortedArray) {
        if (   ![[dict objectForKey:categoryId] isEqualToString:@""]
            && ![[dict objectForKey:categoryId] isEqualToString:@"sign"]
            && ![[dict objectForKey:categoryId] isEqualToString:@"key"]
            )
        {
            [contentString appendFormat:@"%@=%@&", categoryId, [dict objectForKey:categoryId]];
        }
    }
    //添加商户密钥key字段
    [contentString appendFormat:@"key=%@", _partnerkey];
    //得到MD5 sign签名
    NSString *md5Sign =[self md5:contentString];
    
    return md5Sign;
}

6.创建发起支付时的sige签名

//创建发起支付时的sige签名
-(NSString *)createMD5SingForPay:(NSString *)appid_key partnerid:(NSString *)partnerid_key prepayid:(NSString *)prepayid_key package:(NSString *)package_key noncestr:(NSString *)noncestr_key timestamp:(UInt32)timestamp_key{
    NSMutableDictionary *signParams = [NSMutableDictionary dictionary];
    [signParams setObject:appid_key forKey:@"appid"];
    [signParams setObject:noncestr_key forKey:@"noncestr"];
    [signParams setObject:package_key forKey:@"package"];
    [signParams setObject:partnerid_key forKey:@"partnerid"];
    [signParams setObject:prepayid_key forKey:@"prepayid"];
    [signParams setObject:[NSString stringWithFormat:@"%u",timestamp_key] forKey:@"timestamp"];
    
    NSMutableString *contentString  =[NSMutableString string];
    NSArray *keys = [signParams allKeys];
    //按字母顺序排序
    NSArray *sortedArray = [keys sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
        return [obj1 compare:obj2 options:NSNumericSearch];
    }];
    //拼接字符串
    for (NSString *categoryId in sortedArray) {
        if (   ![[signParams objectForKey:categoryId] isEqualToString:@""]
            && ![[signParams objectForKey:categoryId] isEqualToString:@"sign"]
            && ![[signParams objectForKey:categoryId] isEqualToString:@"key"]
            )
        {
            [contentString appendFormat:@"%@=%@&", categoryId, [signParams objectForKey:categoryId]];
        }
    }
    //添加商户密钥key字段
#warning 注意此处一定要添加上商户密钥 别忘了改
    [contentString appendFormat:@"key=%@", @"partnerkey"];
    NSString *result = [self md5:contentString];
    return result;
}
-(NSString *) md5:(NSString *)str
{
    const char *cStr = [str UTF8String];
    //加密规则，因为逗比微信没有出微信支付demo，这里加密规则是参照安卓demo来得
    unsigned char result[16]= "0123456789abcdef";
    CC_MD5(cStr, (CC_LONG)strlen(cStr), result);
    //这里的x是小写则产生的md5也是小写，x是大写则md5是大写，这里只能用大写，逗比微信的大小写验证很逗
    return [NSString stringWithFormat:
            @"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",
            result[0], result[1], result[2], result[3],
            result[4], result[5], result[6], result[7],
            result[8], result[9], result[10], result[11],
            result[12], result[13], result[14], result[15]
            ];
}