UITextField has a lot of things drawn ontop of it's self. Background drawings are going to be covered up by all of those things. To test this you can programatically remove all subviews and see if your " m3" shows up.
for(UIView *subview in textField.subviews) [subview removeFromSuperview];
I think you are going to have to set a default text, then modify the input text whenever a new character is entered. Set up a UITextViewDelegate and overload the function shouldChangeCharactersInRange
:
- (BOOL) textField: (UITextField *)theTextField shouldChangeCharactersInRange: (NSRange)range replacementString: (NSString *)string {
//Do some string manipulation in here to remove the "m3", then add the user's input, then replace the "m3"
}