iOS Swift 3 present MFMailComposeViewController leads to crash - ios

Question

Hey I am using this code to send an email from within my app
#IBAction func sendEmail(_ sender: Any) {
let composeVC = MFMailComposeViewController()
composeVC.mailComposeDelegate = self
// Configure the fields of the interface.
composeVC.setToRecipients(["test#gmail.com"])
composeVC.setSubject("Feedback")
composeVC.setMessageBody("", isHTML: false)
// Present the view controller modally.
self.present(composeVC, animated: true, completion: nil) //CRASHES
}
func mailComposeController(_ controller: MFMailComposeViewController,
didFinishWith result: MFMailComposeResult, error: Error?) {
// Check the result or perform other tasks.
// Dismiss the mail compose view controller.
controller.dismiss(animated: true, completion: nil)
}
The app is live and emails from users do reach me. Often they are empty except for "Sent from my iPhone" but I don't think that's a programming issue. What is an issue tho is that apparently, last week, 8 devices dropped a crash report because of the "//CRASHES" line.
I think the simulator crashes when trying to do this but I haven't used the simulator for this installation for weeks so those crashreports on iTunesConnect are legit crashes.
What happens if the user doesn't have the email app installed?

Answer 1

You can verify that the user has setup the device for sending mail by calling
[MFMailComposeViewController canSendMail]
before performing any actions

Answer 2

According to Apple Documentation MFMailComposeViewController
Before presenting the mail compose view controller, always call the the canSendMail() method to see if the current device is configured to send email. If the user’s device is not set up for the delivery of email, you can notify the user or simply disable the email dispatch features in your application. You should not attempt to use this interface if the canSendMail() method returns false.
So, initialization of mail compose view controller using MFMailComposeViewController() returns nil, if the user’s device is not set up for the delivery of email and app is terminating due to present a nil modal view controller.
Therefore, before presenting the mail compose view controller you should alway check device's mail settings.
So try this lines of code
#IBAction func sendEmail(_ sender: Any) {
if !MFMailComposeViewController.canSendMail() {
print("Mail services are not available")
return
}
let composeVC = MFMailComposeViewController()
composeVC.mailComposeDelegate = self
// Configure the fields of the interface.
composeVC.setToRecipients(["test#gmail.com"])
composeVC.setSubject("Feedback")
composeVC.setMessageBody("", isHTML: false)
// Present the view controller modally.
self.present(composeVC, animated: true, completion: nil) //CRASHES
}