IOS实现微信授权登录功能

<key>NSAppTransportSecurity</key>
<dict>
 <key>NSAllowsArbitraryLoads</key>
 <true/>
</dict>

-(IBAction)sendAuthRequest
{ 
 //构造SendAuthReq结构体 
 SendAuthReq* req =[[[SendAuthReq alloc ] init ] autorelease ];
 req.scope = @"snsapi_userinfo" ;
 req.state = WXPacket_State ;//用于在OnResp中判断是哪个应用向微信发起的授权，这里填写的会在OnResp里面被微信返回
 //第三方向微信终端发送一个SendAuthReq消息结构
 [WXApi sendReq:req]; 
}

//微信代理方法
- (void)onResp:(BaseResp *)resp
{
  SendAuthResp *aresp = (SendAuthResp *)resp;
  if(aresp.errCode== 0 && [aresp.state isEqualToString:WXPacket_State])
  {
   NSString *code = aresp.code;
   [self getWeiXinOpenId:code];
  }
}
//通过code获取access_token，openid，unionid
- (void)getWeiXinOpenId:(NSString *)code{
 NSString *url =[NSString stringWithFormat:@"https://api.weixin.qq.com/sns/oauth2/access_token?appid=%@&secret=%@&code=%@&grant_type=authorization_code",AppId,AppSerect,code];
 dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
  NSURL *zoneUrl = [NSURL URLWithString:url];
  NSString *zoneStr = [NSString stringWithContentsOfURL:zoneUrl encoding:NSUTF8StringEncoding error:nil];
  NSData *data = [zoneStr dataUsingEncoding:NSUTF8StringEncoding];
  dispatch_async(dispatch_get_main_queue(), ^{
   if (data){
    NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
    NSString *openID = dic[@"openid"];
    NSString *unionid = dic[@"unionid"];
   }
  });
 });
}