public function setAPNSPemAsString($pemContent, $passphrase) {
        if (isset($this->handlers[Types::OS_IOS]) && $this->handlers[Types::OS_IOS] instanceof AppleNotification) {
            /** @var AppleNotification $appleNotification */
            $appleNotification = $this->handlers[Types::OS_IOS];
            $appleNotification->setPemAsString($pemContent, $passphrase);
        }
    }