Make First Call PHP File

first.php

<?php

// 1. Autoload the SDK Package. This will include all the files and classes to your autoloader
require __DIR__  . '/php-client/autoload.php';

// 2. Provide your Token. Replace the given one with your app Token
// https://accounts.blockcypher.com/dashboard
$token = 'c0afcccdde5081d6429de37d16166ead';
$apiContext = new \BlockCypher\Rest\ApiContext(
	new \BlockCypher\Auth\SimpleTokenCredential($token)
);

// 3. Lets try to create a new webhook using WebHook API mentioned here
// http://dev.blockcypher.com/#webhooks
$webHook = new \BlockCypher\Api\WebHook();
$webHook->setUrl("https://requestb.in/slmm49sl?uniqid=" . uniqid());
$webHook->setEvent('unconfirmed-tx');

// 4. Make a Create Call and Print the Card
try {
    $webHook->create($apiContext);
    echo $webHook;
}
catch (\BlockCypher\Exception\BlockCypherConnectionException $ex) {
    // This will print the detailed information on the exception. 
    //REALLY HELPFUL FOR DEBUGGING
    echo $ex->getData();
}

Warning: sizeof(): Parameter must be an array or an object that implements Countable in C:\FILES\XAMPP\htdocs\project\php-client\blockcypher\php-client\lib\BlockCypher\Common\BlockCypherModel.php on line 315

Warning: sizeof(): Parameter must be an array or an object that implements Countable in C:\FILES\XAMPP\htdocs\project\php-client\blockcypher\php-client\lib\BlockCypher\Common\BlockCypherModel.php on line 315
{"error": "API calls limits have been reached. To extend your limits please upgrade your plan on BlockCypher accounts page."}

Who knows how to fix it please?

Just put "@" symbol before sizeof() to hide these warning messages

Move the first and second conditions

From
} else if (sizeof($v) <= 0 && is_array($v)) {

to the
} else if (is_array($v) && sizeof($v) <= 0) {