Get value from nested json php - php

Question

I am receiving data from a webhook with the following code below.
<?php
$inputJSON = file_get_contents('php://input');
$input = json_decode($inputJSON, TRUE);
$myfile = fopen("callback.txt", "a") or die("Unable to open file!");
$txt = $input["payload"]["type"];
fwrite($myfile, "\n". $txt);
fclose($myfile);
http_response_code(200);
?>
I am trying to get the 'type' value from the retuned output. I have found that using an if statement inside a for each loop would do the job. However i'm sure this isn't an ideal solution. is there a more direct way of getting that element?
The code above is outputting an empty text file.
and the documentation shows the json should be in the following format:
{
"action": "add",
"collection": "broadcast",
"payload": {
"author": "Sveninge Bambuser",
"created": 1474033783,
"customData": "",
"height": 540,
"id": "9353eaec-794f-11e6-97c0-f19001529702",
"ingestChannel": "cfc8626c-9a0e-ab78-6424-3eb0978d8e45",
"lat": 63.205312,
"length": 0,
"lon": 17.13011,
"positionAccuracy": 25,
"positionType": "GPS",
"preview": "https://archive.bambuser.com/9353eaec-794f-11e6-97c0-f19001529702.jpg",
"resourceUri": "https://cdn.bambuser.net/broadcasts/9353eaec-794f-11e6-97c0-f19001529702?da_signature_method=HMAC-SHA256&da_id=9353eaec-794f-11e6-97c0-f19001529702&da_timestamp=1474033783&da_static=1&da_ttl=0&da_signature=eaf4c9cb29c58b910dcbad17cf7d8a3afa4e6a963624ba4c4fd0bb5bade1cdd6",
"tags": [
{
"text": "whoa"
}
],
"title": "Amazing!",
"type": "live",
"width": 960
},
"eventId": "93df93061a891c23"
}

Answer 1

I replaced:
$txt = $input["payload"]["type"];
with:
$txt = $input['payload']['type'];
it appears to be the double quotes causing the issue.