(iOS) How to make custom keyboard background transparent

Question

As a title, how to make it transparent for iPad?
because it’s too ugly to see the gray outside.
Thanks.

Regards,
GRTan.

Screenshot:

EDIT:
Sorry I forgot about the source code.
Source Code Here . (UPDATED)

Answer 1

Insert next line

defaultLNNumberpad.backgroundColor = [UIColor whiteColor];

after

defaultLNNumberpad = [[[NSBundle mainBundle] loadNibNamed:@"LNNumberpad" owner:self options:nil] objectAtIndex:0];

in the LNNumberpad.m file .

http://i.stack.imgur.com/wLQOj.png