在PHP中将带斜杠的JSON转换为数组

我有一个我正在使用的API的JSON示例，我想转换为Array

{
"function":"BEEP.postPayment",
"payload":"{\"credentials\":{\"username\":\"api_user\",\"password\":\"!*****\"},\"packet\": [{\"MSISDN\":\"0473949\",\"amount\":\"5\",\"serviceID\":54,\"currencyCode\":\"RIA\",\"nar ration\":\"Pay dstv\",\"accountNumber\":\"5285990\",\"extraData\":\"\",\"datePaymentReceived\":\"2018-08 -22 11:46:22\",\"payerTransactionID\":\"SBC20180822114622\",\"customerNames\":\"Simon uyar\"}]}"
}

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如何在PHP中转换它？

索引

有效负载

包含JSON:

$array = json_decode($json, true);
$payload = json_decode($array['payload'], true);