system/CodeIgniter.php
public function displayCache($config)
	{
		if ($cachedResponse = cache()->get($this->generateCacheName($config)))
		{
			$cachedResponse = unserialize($cachedResponse);
			if (! is_array($cachedResponse) || ! isset($cachedResponse['output']) || ! isset($cachedResponse['headers']))
			{
				throw new Exception('Error unserializing page cache');
			}

			$headers = $cachedResponse['headers'];
			$output  = $cachedResponse['output'];

			// Clear all default headers
			foreach ($this->response->getHeaders() as $key => $val)
			{
				$this->response->removeHeader($key);
			}

			// Set cached headers
			foreach ($headers as $name => $value)
			{
				$this->response->setHeader($name, $value);
			}

			$output = $this->displayPerformanceMetrics($output);
			$this->response->setBody($output);

			return $this->response;
		}

		return false;
	}
public function displayCache($config)
	{
		if ($cachedResponse = cache()->get($this->generateCacheName($config)))
		{
			$cachedResponse = unserialize($cachedResponse);
			if (! is_array($cachedResponse) || ! isset($cachedResponse['output']) || ! isset($cachedResponse['headers']))
			{
				throw new Exception('Error unserializing page cache');
			}

			$headers = $cachedResponse['headers'];
			$output  = $cachedResponse['output'];

			// Clear all default headers
			foreach ($this->response->getHeaders() as $key => $val)
			{
				$this->response->removeHeader($key);
			}

			// Set cached headers
			foreach ($headers as $name => $value)
			{
				$this->response->setHeader($name, $value);
			}

			$output = $this->displayPerformanceMetrics($output);
			$this->response->setBody($output);

			return $this->response;
		}

		return false;
	}
Determines if a response has been cached for the given URI.

@param \Config\Cache $config

@throws \Exception

@return boolean|\CodeIgniter\HTTP\ResponseInterface