How to prevent crash on Cancel of MFMailComposeViewController?

Question

Somewhere:

if([MFMailComposeViewController canSendMail])
{
    MFMailComposeViewController *email_vc = [[MFMailComposeViewController alloc] init];
    email_         


        

Answer 1

I guess the action sheet gets the dismiss message instead of the mail compose view controller.

Not quite.

The sequence of events probably happens like this:

• Action sheet calls -actionSheet:clickedButtonAtIndex: on its delegate (the MFMCVC).
  • MFMailComposeViewController calls -mailComposeController:didFinishWithResult:error: on its delegate (your VC)
    • Your VC calls [self dismissModalViewControllerAnimated:NO]
      • This causes the MFMCVC to be released. Since the dismiss isn't animated, there is no longer anything referring to the MFMCVC. It gets dealloced!
• Action sheet calls -actionSheet:didDismissWithButtonIndex: on its delegate
  • But its delegate has been dealloced!
    • So it crashes!

The fix would be for Apple to do actionSheet.delegate = nil in -dealloc.

A potential workaround

[[self.modalViewController retain] autorelease]
[self dismissModalViewControllerAnimated:NO]

This is a bit trickier to do if you are using ARC.