string format example

    NSNumber *quantity = [NSNumber numberWithDouble:1];
    NSNumber *price_vat = [NSNumber numberWithDouble:0.76];

    double totalPrice = 293;

    totalPrice = totalPrice + [quantity doubleValue] * [price_vat doubleValue];

    NSString *s = [NSString stringWithFormat:@"%0.2f", totalPrice];

    NSLog(@"total: %@", s);

    // in case we're testing without the IBOutlet connected,
    //  don't try to set its .text
    if (nil != self.priceLabel) {
        self.priceLabel.text = s;
    }