public function setLogger(ApnsPHP_Log_Interface $logger)
	{
		if (!is_object($logger)) {
			throw new ApnsPHP_Exception(
				"The logger should be an instance of 'ApnsPHP_Log_Interface'"
			);
		}
		if (!($logger instanceof ApnsPHP_Log_Interface)) {
			throw new ApnsPHP_Exception(
				"Unable to use an instance of '" . get_class($logger) . "' as logger: " .
				"a logger must implements ApnsPHP_Log_Interface."
			);
		}
		$this->_logger = $logger;
	}