问题
Has anyone faced an issue where the MFMailcomposeviewcontroller send button is disabled/grayed out? The cancel button works perfectly fine.
It seems like a new bug?
回答1:
This could happen in case native Mail application is removed from iPhone (allowed starting from iOS 10). In this case system Setting missing "Mail" setting item and system probably cannot get configuration of default email account.
At the same moment MFMailComposeViewController.canSendMail() return true, so I did not find any solution to solve this case.
回答2:
Make sure the Mail App is installed in your device.
回答3:
Getting same issue and spent few hours to find out the solution and working fine now.
1)check default "Mail" app of your ios device is uninstall
or
2)already exist but offload this app from setting that time showing icon like attached image than just install app again and solve the problem.
来源：https://stackoverflow.com/questions/40541055/mfmailcomposeviewcontroller-send-button-is-disabled