If you hadn't noticed you can change the iOS keyboard type quite easily with one line:
[textField setKeyboardType:UIKeyboardTypeNumberPad];
in "mojo/native/mojo.ios.cpp" after line 1049 (which reads: textField.text=@"";).
More constants:
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).
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