How to get keyboard to popup when UITabBar item is tapped

I have a UITabBarController, in which one of the views is a MFMailComposeViewController.

Is there any way I can get the keyboard to show when the tab for this view is tapped, rather than the text 开发者_如何学Gofield for the email address?

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Since MFMailComposeViewController inherits from UIResponder, you should be able to call:

[myMailComposeViewController becomeFirstResponder];