安卓、ios APP调用微信支付时，页面出现空白

我的后端是用php开发的。我是先调用微信的统一下单生成，生成prepay_id预支付订单号，代码如下：

public function send_pay(){

//使用统一支付接口

$unifiedOrder = new UnifiedOrder_pub();

$amount = trim($this->config['money'])*100;

$notify_url=$this->config['NotifyUrl']; //通知URL

//设置统一支付接口参数

//设置必填参数

//appid已填,商户无需重复填写

//mch_id已填,商户无需重复填写

//noncestr已填,商户无需重复填写

//spbill_create_ip已填,商户无需重复填写

//sign已填,商户无需重复填写

//iconv("gb2312","utf-8//IGNORE",

$unifiedOrder->setParameter("body",$this->config['title']);//商品描述

//自定义订单号，此处仅作举例

$out_trade_no = $this->config['code'];

$create_ip = $_SERVER["REMOTE_ADDR"];

$unifiedOrder->setParameter("out_trade_no",$out_trade_no);//商户订单号

$unifiedOrder->setParameter("total_fee",$amount);//总金额

$unifiedOrder->setParameter("notify_url",$notify_url);//通知地址

$unifiedOrder->setParameter("spbill_create_ip",$create_ip);//用户端实际ip

$unifiedOrder->setParameter("trade_type","APP");//APP交易类型

$unifiedOrder->setParameter("attach","111");//附加数据

//获取统一支付接口结果

$unifiedOrderResult = $unifiedOrder->getResult();

//商户根据实际情况设置相应的处理流程

if ($unifiedOrderResult["return_code"] == "FAIL")

{

//商户自行增加处理流程

echo "通信出错：".$unifiedOrderResult['return_msg']."
";

}

elseif($unifiedOrderResult["result_code"] == "FAIL")

{

//商户自行增加处理流程

echo iconv("utf-8","gb2312//IGNORE","错误代码：".$unifiedOrderResult['err_code']."
");

echo iconv("utf-8","gb2312//IGNORE","错误代码描述：".$unifiedOrderResult['err_code_des']."
");

}

elseif($unifiedOrderResult["return_code"] == "SUCCESS")

{

/**

成功后返回如下信息

**/

$result = array();

$result['appid'] = $unifiedOrderResult['appid'];

$result['partnerid'] = $unifiedOrderResult['mch_id'];

$result['prepayid'] = $unifiedOrderResult['prepay_id'];

$result['noncestr'] = $unifiedOrderResult['nonce_str'];

$result['timestamp'] = time();

$result['package'] = "Sign=WXPay"; //'Sign=WXPay'

$result['sign'] = $unifiedOrderResult['sign'];

echo json_encode($result);

exit;

//商户自行增加处理流程

//......

}

}

?>

将生成的下面这几个参数发给安卓、ios那边：

$result['appid'] = $unifiedOrderResult['appid'];

$result['partnerid'] = $unifiedOrderResult['mch_id'];

$result['prepayid'] = $unifiedOrderResult['prepay_id'];

$result['noncestr'] = $unifiedOrderResult['nonce_str'];

$result['timestamp'] = time();

$result['package'] = "Sign=WXPay"; //'Sign=WXPay'

$result['sign'] = $unifiedOrderResult['sign'];

但是，安卓、ios那边调用微信支付时居然显示空白，什么出错提示也没有，如下截图：