UIPopover Behaviour
===

I have a popup view (of a calculator) that is presented whenever a textfield begins to be edited.  The code where the display method is called, and the display method itself are posted below.

    -(BOOL)textFieldShouldBeginEditing:(UITextField *)textField {
        
        //the background color may have been yellow if someone tried to submit the form with a blank field
        textField.backgroundColor = [UIColor whiteColor];
        
        sender = @"text field";
        
        [self displayCalculator:textField.frame];
        
        return YES;
    }

The method that displays the view is :

    -(IBAction)displayCalculator:(CGRect)rect{
        
        calculator = [[CalculatorViewController alloc] initWithNibName:@"CalculatorViewController" bundle:nil];
        popoverController = [[[UIPopoverController alloc] initWithContentViewController:calculator] retain];
    		
        [popoverController setPopoverContentSize:CGSizeMake(273.0f, 100.0f)];
            
        [popoverController presentPopoverFromRect:rect inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
            
    }


My questions are:

1)  How can I get the popover to stay?  I would like the user to be able to click the textfield (the textfield that presented the popup in the first place), but when they do, the popup disappears.

2)  The popup sometimes appears in such a way that it blocks the textfield, is there anyway that I can control where the popup appears?  I am currently passing the frame of the textfield but that doesn't appear to be working  