Your answer can be found here: Programmatically change UITextField Keyboard type
To summarise...
You can change the keyboard type by doing the following:
[textField setKeyboardType:(TYPE)];
Replacing (TYPE) with one of the following:
UIKeyboardTypeDefault,                // Default type for the current input method.
UIKeyboardTypeASCIICapable,           // Displays a keyboard which can enter ASCII characters, non-ASCII keyboards remain active
UIKeyboardTypeNumbersAndPunctuation,  // Numbers and assorted punctuation.
UIKeyboardTypeURL,                    // A type optimized for URL entry (shows . / .com prominently).
UIKeyboardTypeNumberPad,              // A number pad (0-9). Suitable for PIN entry.
UIKeyboardTypePhonePad,               // A phone pad (1-9, *, 0, #, with letters under the numbers).
UIKeyboardTypeNamePhonePad,           // A type optimized for entering a person's name or phone number.
UIKeyboardTypeEmailAddress            // A type optimized for multiple email address entry (shows space @ . prominently).
The one you are looking for (shows @ and .com) is UIKeyboardTypeEmailAddress