Present MFMailComposeViewController

class ViewController: UIViewController {

	/* … */

	private func presentMailComposer() {
		guard MFMailComposeViewController.canSendMail() else { return }
		let composer = MFMailComposeViewController()
		composer.mailComposeDelegate = self
		composer.setMessageBody("Hello!", isHTML: false)
		composer.setSubject("Hello!")
		composer.setToRecipients(["address@example.com"])
		present(composer, animated: true)
	}

}

extension ViewController: MFMailComposeViewControllerDelegate {
	
	func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
		controller.dismiss(animated: true)
	}
	
}