There are a couple of options open to you, you need to decide when you want to dismiss your textfields numeric keyboard. For example, if you have a set number of digits you need before you dismiss you could subscribe to
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(textFieldTextDidChange:) name:UITextFieldTextDidChangeNotification object:nil];
Then in implement something along the lines of
-(void)textFieldTextDidChange:(NSNotification *)notification
{
UITextField *textfield = notification.object;
if(textfield.text.length == NUMBER_OF_DIGITS_NEEDED)
[textField resignFirstResponder];
}
If your user also needs to be able to dismiss the keyboard at their discretion, you should put a tap gesture recognizer on the remaining visible view.
UITapGestureRecognizer *tapGestureRecogniser = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTapGesture:)];
tapGestureRecogniser.delegate = self;
[self.view addGestureRecognizer:tapGestureRecogniser];
-(void)handleTapGesture:(UITapGestureRecognizer *)tapGestureRecogniser
{
if ([self.myTextField isFirstResponder])
[self.myTextField resignFirstResponder];
}