MFMailComposeViewControllerDelegate protocol defines the method that your delegate must implement to manage the mail composition interface. The method of this protocol notifies your delegate object when the user has finished with the interface and is ready to dismiss it.
Your delegate object is responsible for dismissing the picker when the operation completes. You do this using the
dismissModalViewControllerAnimated: method of the parent view controller responsible for displaying the
MFMailComposeViewController object’s interface.
mailComposeController(_:didFinishWithResult:error:) - mailComposeController:didFinishWithResult:error:
Tells the delegate that the user wants to dismiss the mail composition view.
The view controller object managing the mail composition view.
The result of the user’s action.
If an error occurred, this parameter contains an error object with information about the type of failure.
Your implementation of this method should dismiss the mail composition view. Implementation of this method is optional but expected.
If the user has opted to send the email created by this interface, that email should be queued in the user’s Mail program by the time this method is called. If an error occurred while queueing the email message, the
errorparameter contains an error object indicating the type of failure that occurred.
Available in iOS 3.0 and later.